My back gets weak between the shoulder blades. I actually had to go to the ER because it felt like the wind was knocked out of me every time I moved my arms in front of me to lift something. I was told it's a rhomboid strain, but this happens quite often. I take generic mestinon and it helps a lot.

Years back I tested positive, then the next test was neutral. There were a couple of negatives through the years and now it's positive again. I'm not sure if the tests came back negative because I used to be a heavy caffeinated soda drinker and caffeine works as an anti cholinesterase like Mestinon. I only drink tea maybe once a day now when I feel the Mestinon wear off too quickly. So, that may be the reason it's positive now.