Any Pennsylvania patient younger than 18 needs a caregiver to register for them. The minor's parent, legal guardian, or spouse can easily become their caregiver one the state registration website. Unfortunately, as an online service, we're legally not allowed to accept minors, even with parental consent.
We recommend doing a search using something like Yelp.com and the term "Medical Marijuana Evaluation" and you should have no problem finding a few MMJ doctors in your area to help.