Imuran and Apriso?

My doctor prescribed Imuran in January when it became clear that Apriso and messalimine enemas (nightly) weren't controlling my UC. Because I read that they would suppress my immune system, and even worse, cause fatigue, I chose to continue on with what I had been using. Recently, my bloody diarrhea has become much worse and I have decided to start the Imuran. At the time, my doctor had told me to continue with the Apriso and enema with the Imuran. When I checked drug interaction on expocrates.com, I saw that using the Apriso with the Imuran had a caution warning. My doctor did give me a lab slip to have my blood checked 2 weeks after starting the Imuran. My question to the forum is do you recommend that I quit the Apriso and just wait for the Imuran to kick in, or hope for the best and use the Apriso with it? I do plan to call my doctor, but wanted to find out if any of you have used both and what the consequences were.

Thanks so much for the advice! I know how helpful these forums are!