Are you on a steroid now? If so, the fact that you produced any antibodies should tell a doctor that you have MG! Steroids suppress the immune system that produces the antibodies! So, in other words, your antibody test could be a false negative (or a false borderline).
What do you mean by steroid resistant?
Have you been tested for celiac disease? Vit. B12 or other deficiencies such as Vit. D?
What you are describing sounds a lot like MG. The swallowing issues, too. Don't assume everything is due to Crohn's!
You should know that MG doesn't like to be pushed, and that is exactly what you're doing at the gym. MG WILL push back, and you could become progressively worse in a short period of time. You really don't want to go into a MG crisis!! Working out also raises your body temperature. MG becomes much worse in hot weather, exercising, having an infection, or anything else that heats the body up (yeah, sex, too).
Who ran the AChR blood tests? Ask that doctor to get a referral to Mayo pronto! With MG, you can't wait until January.
I hope you can get some help right away!
Annie