I Have Had Serious Panic Anxiety Disorder And Social Anxierty

I have had serious panic anxiety disorder and social anxierty disorder, along with mild depression for over 20 years. I am 64 year old white female with a great husband, job and family. My psychiatrist has had me on the same meds this whole time. Does your body become immune to them? I take Zoloft and Diazepam. I recently am very fatigued and have developed IBS diarrhea. Went to a gastro doctor with a colonoscopy and all was fine...yet the immediate flare of diarrhea comes a lot. I also put on 65 pounds, have dry mouth, and my body gets very warm and sweaty a lot. Any suggestions, especially about the weight?