Why did my left testicle hurt in the morning when i walked and then i went to a doctor and the doctor said it was normal and right now it hurting when sitting down or touched?

There is no clear way of answering your question without examining you. Let go with a hypothetical. Your doctor probably ruled out an infection or an acute torsion. I don't know if you had an ultrasound or a good physical examination that could rule out a Hydrocele or a Varicocele. If that was ruled out then there can be a problem at the sperm cord.or the nutcracker syndrome The list continues

Wear a good supporting underwear. It can happen when the testicle is compressed or irritted when it is inadertantly in a wrong position. You should be fine.