Dave, Welcome. I'm sorry you have gone out of remission. I'm sorry to say that it does happen. No two people who have MG have the same history with MG.
Physical stress, overdoing it, infections, surgery, not enough sleep and so many other things can make MG worse.
You should talk to your neurologist about all of this too, including the exercise issue. The worse you get, the less you can exercise. Why? Because exercise can make you much worse if your MG is doing badly. It might even put you into a crisis a couple days later. MG has that odd "collective" effect after you do things. It may not show up until a couple days later.
There have been studies on the effects of tetrahydrocannabinol/THC (from marijuana) on acetylcholinesterase but not enough studies to put your life at risk by smoking it! I'm all for alternative medicine but smoking anything adversely effects the immune system.
http://www.ncbi.nlm.nih.gov/pubmed/693562
http://www.ncbi.nlm.nih.gov/pubmed/126214
Prednisone can be a dangerous drug, with a lot of side effects. You have to think about the long term problems with it, especially how damn hard it is to withdraw from. Are you willing to be on it for the rest of your life? Seriously, it's that hard to get off of. Research it, talk to people who have had it. I've known lupus patients who had to have pins put into their hands due to the bone demineralization from Pred. Only you can decide what you're willing to deal with. But if you got strep so easily, you also have to think about how easy it is to get infections while on immunotherapy.
In some MGers, double vision is a big deal and really has a big impact on their life. I don't know if I've just gotten used to it or what but I can deal on Mestinon alone. Again, talk to your neuro about all of this. You could try cold washcloths on your eyes or go see a neuro-ophthalmologist for suggestions.
There are no easy answers with MG. One of the best "treatments" you can use is alternating activity with rest. No, it's not fun but that's the reality of MG. If you push too hard, MG pushes back.
I hope you and your doc can figure out what to do. It would be great if we all could go into remission.
Annie