I have been taking Synthroid 0.075 for about 2 years and have been experiencing dizziness lately It comes and goes and is very quick when it occurs. it has been going on now for about an hour occuring every 2-3 minutes. Comes and goes quickly. I am 52 yrs old and weigh 105 and good health otherwise. Could this be a new symptom of the hypothroid? I have not experienced this.