That is exactly what happened to me after 1 1/2 years on Remicade. Worked great at first but, after a while, it only lasted about
6 weeks then 4 then maybe 2 weeks. They gave me a blood test and there was no Remicade in my system. It seems I had developed antibodies to it. The doctor said I should go on Humira but my insurance company would not pay for it and I couldn't afford thousands of dollars per month. Seeing my dilema, my doctor worked with me using Chinese herbs and that has been a lifesaver for me. I am doing better these days than I was when I was on Remicade!
You should get a blood test (I think it's a Promethius test?) to see if the Remicade is still in your system. Mary