I Have Ben Taking Tramadal For Pain, Waiting To Have

I have ben taking Tramadal for pain, waiting to have back surgery, I have been on this drug for about 6 weeks. I have a very sensitive tummy, due to a partial colonectomey. So I do have a script for Phenergen 25 mg. I was wondering if I can take 50 mg at the same time, because I can not get my yummy to feel betterm So its deal with pain, or just feel really sick and not able to eat. thank you