I Am A 73 Year Old Woman Who Has Been

I am a 73 year old woman who has been given bupropionHCI SR 150mg sustained- relief for anxiety and I think it is causing me constipation. I have been having trouble for a couple of weeks and am having knee surgery next week and want my bowels to move better. I had no trouble before taking this medicine. My doctor said to quit it for a while and see what happens. I am also taking Cymbalta 20mg for pain. Omeprazole 20 mg for gerd, Synthroid 88mcg. For the past two weeks I have taken stool softeners and MeriLax and it won't work. Can you give me any ideas before I have surgery?