I was diagnosed with RA in 2005 and I have been to WDW four times since then. I will tell you what works for ME and what my rheumatologist recommends. She gives me a cortisone shot (deposit-medrol) in my hip about two weeks before a trip. She also tells me to use Tylenol Arthritis as it is extended release in the morning. If I start feeling pain, to step it up to Tylenol 3. Now, it sounds like you cannot use Tylenol but perhaps you have another painkiller you can use. I take my Rx anti-inflammatory every morning. I would also recommend that you pace yourself during the day. Either go back to the hotel, so you and the kids can take a break, have a TS meal mid day (that will give you a good break in the AC) or do a longer show that allows you to sit and rest. Good ones might be COP in MK, Universe of Energy in Epcot, Beauty and the Beast in DHS, and either Lion King or Nemo in AK.
On vacation, the pool is my friend. I like to do range of motion exercises in it. I think one of the most important things is to be careful that you do not overdo it the first day or two and then be in pain for the rest of the trip. Your kids are young - they will enjoy shorter park days also. Have a wonderful time.
Oh, and if you are on a biologic, make sure the hotel fridge stays cold enough and I like to put a note on it saying that medication is inside.
