For Over Two Weeks I've Been Having Stomache Upset, Light

For over two weeks I've been having stomache upset, light diarrhea and some nausea. I've also had a fair amount of dizziness. I used the whole month of June to wean myself off of Effexor, then started taking armor thyroid after being on synthroid for thirty years. I also struggle with sinus/allergies a lot, so not sure if all these issues are sinus or gut related.