"flareups" sorry it is a repost since my last email was invalid

I have been on Enbrel, hydrochloroquine and folic acid for several months and it seemed like it was working for me for the most part. I always had some pain/discomfort, joint popping sounds and range of motion problems in my elbows but for the most part the pain and limited mobility went away after a few months of treatment. A few days ago my feet swelled up again, got very painful and it is making walking darn near impossible. I can feel my hands swelling again too like before I received treatment. I called my Rheumatologist and he just put me on Sulfasalazine yesterday. I see this also takes a long time to work. Are these "flare ups" something occurs often for people with RA? I know I am somewhat lucky (if you can call it that) that so far all I have are "flare ups" since some people have terrible symptoms all the time but any information will certainly help.