Is it normal for a toddler to drag the toes of one foot when walking?

Personally, I don't think it is normal. You are right to feel concerned. You need to fire that doctor and go find another who is compionate to your concerns. You are not a doctor. You didn't go to medical school. He shouldn't expect you to know what is normal for your son and what is not. That is his job. Plus, he should know EVERYTHING that your son is doing, normal or not.