Why am I light headed all of a sudden?

I was diagnosed with Graves Disease several years ago. I have been taking 25 mg of Methimazole twice a day for the past 9 months, and all of a sudden I am very light headed and sometimes side-step like I am drunk (I also feel like I am drunk). This just started today. Over the past few weeks I have had an on-again-off-again sore throat accompanied by an achy jaw and headache. I have also been feeling very tired and irritable lately. I seem to lack all motivation whatsoever. I went to my hospital to have labs done on Wednesday, but my doctor has not called me back yet. I guess I'm getting a little worried and here it is, after business hours on Friday, and I can't call my doctor until Monday. I have heard of thyroid storms and I'm afraid that's what's about to happen.