Prolonged stomach pain

I have mental health issues and all my life I have taken antidepressants and such. I've always had constipation problems with taking those meds and I just upped my fiber and dealt with it in other ways. I have since been prescribed lithium for bi polar disorder. It destoyed my stomach in ways that one cannot live with. As soon as I ate I had to go about 25 min later after getting all bloated and gassy. So I weaned myself off of that after being miserable for a couple months. HERE IS THE PROBLEM... It's been about two weeks and things are worse! Now I wake up everyday to bad gas and having to go to the bathroom pretty bad after gettin stomach cramps. I still go to the bathroom after eating like clockwork. It's painful and I don't know what to do? I can't function like this.