Even if it's a side effect of the med, you should still treat your stomach issues, especially if you plan to take the med for a long time. Most doctors understand that you can't discontinue a psych med that's helping you and you have to treat some side effects. Maybe if you call the office and talk to a nurse, or a leave a message for the doctor, they can call something in, or at least recommend what you should be taking over the counter

Your pdoc may be willing to call something in as well...
Mine ordered Zofran for nausea because of the meds I was taking at one point.