Yes, recent changes can cause stomach upset. The different drug manufacturerers all use different fillers (inactive ingredients) in their tablets. Some people are sensitive to these, and a change in brand or from generic to brand or vice versa can make a difference.
As Kristina suggested, please post your recent thyroid labs along with reference range (they vary lab to lab). Also, please include a meds history.
Do you still have hypo symptoms?
I believe most doctors will say 'no'; but any adjustments of the meds, if too much too quickly cause my stomach to be a bit upset. Being hypo, can also cause stomach upsets. It depends when it's happening, what does you're on (have you changed it recently,) and what your latest blood test results show (are you hypo and have you been taking levo for long?