If you are getting serious swelling, you really need to have the joint drained if possible. I have dealt with the very painful swelling in my right knee on and off for 5 years, and both my GI and Rheumatologist have said to get it drained to prevent joint destruction. The first couple years I did not know this and was not under the level of care that I am now, and I still have problems with my one knee even in remission.
If it's fluid that can be drained, you should be able to get this done at a walk-in, or at your PCP. If they won't do it, tell them to get you somewhere that will. Don't take no for an answer, and don't let them delay. Your health is more important than their convenience.
Best of luck to you.