There are not many side-effects with this med. However, indigestion is listed as a common side-effect of Zoloft. Maybe taking it after you had a meal will help? FWIW I have had problems with indigestion shortly after I took many kinds of pills. I do not think it was what I was taking at the time.

IMHO if it happens moments after taking the med, it is probably not the med. The stomach does not have enough time to even start the digestion process, no time for anything to happen that is med related. But I am no doctor.