Is Headaches Normal With Hypothyroidism?

Dear Doctor; I stopped HCG sublingual drops two days ago and have begun adding fats in small amounts very slowly, though no starches or sugars. I've had a severe headache ever since. Is this normal? What can I do to help it? I am 59, have dropped from 162 to 139 lbs. in 5 weeks, am generally healthy with a managed hypo-thyroid condition. Marion