What Causes Itchy Rashes On Scalp, Thighs And Hips While On HCG?

My Dr has prescribed HCG for weight loss. One shot a day for a month....I now have a rash that is very itchy....my scalp, on the backhoe my thighs, on hips....the rash just moves around my body....can it be the HCG? I am 57 years old, 5'6" tall and weigh 200 lbs.