Hello and welcome! We’re fellow patients here, not doctors, so it’s really important to get further direction from your PCP or endocrinologist in terms of further dosing.
I personally had mild nausea when I first started taking methimazole, but I found it got better if I took the meds with food or milk.
Sore throat with fever is a sign of a potentially serious side effect (an extreme reduction in white blood cell count) with methimazole, so if you are experiencing this, definitely let the doctor’s office know ASAP. They will likely have you go in to get white blood cell count checked, just to make sure everything is OK.
You know your body and you know when something is off, so *please* don’t be afraid to be the squeaky wheel and keep calling until someone will listen you you! Your pharmacist could also be a good resource.