I have had a shoulder issue for sometime now, and after 3 cortisone shots, and 2 trips to PT, and lots of acupuncture, it keeps on coming back. Going for second opinion soon, afraid I will need surgery, if so, everything stops for a while. Was diagnosed as a minor rotator cuff tear, almost a year ago, and now it’s waking me up at night. 
 

have call in, waiting for call back to schedule 2nd opinion 

Hang in there, @WalterJ!! I believe it’s smart to get second opinions, especially when health is the issue. The floor will be there with open arms whenever you’re ready to return. Take care of your health first and foremost. 

Going to be a long summer. Second opinion on shoulder is not until September, I thought it would be sooner.

I've had a minor rotator cuff tear for years (caused by trying to do a bench press with mismatched weights).  Fortunately for me it only flares up at certain times, and I know what will cause it.  I've also seen two members of my dojo deal with (full) rotator cuff tears -- those are no fun.  My training partner for my most recent test had a complete rotator cuff tear that kept him in a sling for several months and it's taken him months to regain strength in that shoulder.   However, the earlier you have the surgery done (after exhausting your other options), the earlier you get to start on your road to recovery.

The other thing to keep in mind is that Karate (and other martial arts) can and should be lifelong pursuits.  As your body and physical condition changes, you modify and alter your training to go with it.  Now if Kobudo is your primary MA focus, then this may be quite difficult, because training with weapons does require quite a bit of shoulder strength; one of our instructors tore her rotator cuff by repeatedly using poor form in Kobudo while trying to find more and more power.  So figure out what you *can* do while you're waiting for the shoulder to get fixed.  As a general rule "if it doesn't feel right, just don't do it".  If working with full-sized weapons is too hard, then work slowly with lightweight ones (for example, have you seen the ones that ATA uses?  they are literally toothpicks!).  If that doesn't work, then just work on your stances and footwork.  One of the things I'm having to do more and more often is learning how to train through and around injuries. 

In any case, what @sensei8 has said is absolutely 100% correct.  The floor will always be there for you when you get back.  Whether you try to train around the injury or you completely take the time off to let your body heal, you can always come back.  The muscle memory will come back pretty quickly and the conditioning won't be too far behind.

I'm sorry that second opinion is so far out, @WalterJ.  Hopefully though, they will have an answer for you.  But, like @aurik said, there's always ways to train around injuries.  Personally, I recommend...kicking!  I would also recommend finding some trusted sources on YouTube to watch to help you keep your material, or whatever it is you want to study, fresh in your mind.  I've spent quite a bit of time reviewing Aikido techniques by watching the videos from our dojo's YouTube page.  It's not the same as training, but it's good for training the mind.  While watching videos like this, I would take notes on various aspects of the techniques, keys to the steps, and things like this.  I found it really helpful and logged them in my journal.  Maybe you can find the same benefit.

Bummer to hear this, WalterJ. Annoying to have to wait. Maybe they'll have a cancellation and can get you in sooner.

Best of luck to you @WalterJ as others have said, take care of your health then get back to training when it makes sense to do so.  Nothing is more important than your heath for your training anyway, without health you can't train. 

Update, got appointment… in September… but it got moved up to August. It can’t get here soon enough. This silly thing wakes me up regularly at 3:30am every morning…. Without fail. 

I don't know how old you are, but rotator cuff injuries are more likely as you get older, and take even longer to heal. I overdid it with archery, and it took over a year to really heal. After 2-3 months of DIY exercises and rest, I went to a PT for about 6 sessions, and did the prescribed exercises religiously. What really helped after that was Yoga, I found a great book called Yoga for Men, that had shoulder specific poses.

1 hour ago, JazzKicker said:

I don't know how old you are, but rotator cuff injuries are more likely as you get older, and take even longer to heal. I overdid it with archery, and it took over a year to really heal. After 2-3 months of DIY exercises and rest, I went to a PT for about 6 sessions, and did the prescribed exercises religiously. What really helped after that was Yoga, I found a great book called Yoga for Men, that had shoulder specific poses.

In a few months i will officially be, by USA standards, a senior citizen. I have been dealing with this for a year, MD, PT, exercises , cortisone injections, acupuncture and it has gotten better at times, but yard work and other responsibilities need to be taken care of and that causes inflammation. For awhile it was manageable, but lately it starts to feel better, but not as good as before and then comes back worse. Now it is making it hard to sleep. So now i will go see what this doctor has to say. 
 

went through a similar thing a few years back with my knee, it eventually was replaced.