Why do symptoms become worse than before when a remicade infusion is due?

My 4th dose was supposed to be due on the 30th April but my GI and I agreed to take it 5 days earlier which means in week 7. I found out the effect of the 3rd dose wore off after only 4 weeks. However, symptoms are becoming worse every day in comparison to the previous day. That was not the case prior to taking Remicade. Both my proctitis and the pain of the perianal fistula have become unbearable. I haven't been able to sleep at night because of pain for 4 days. Isn't this supposed to be a maintenance drug?