i wouldn't leap to the possibility of illicit drug use, although it's a possibility.
you said your son is 15 and adjusting to 10th grade. Not that i am accusing, assuming or judging, It happens all the time.. I would not rule out that he may be using some type of drug ( such as cocaine, or similar ) to help him cope. These drugs are easy to get, easy to hide, but will cause the nose run usually as long as they are using and can continue for weeks after stoping. ... It happens more often then not. I had this happen to someone i know and hidden well.. for a very long time, fooled the doctors, everyone, because it can be anything. but it finally came out. Kids now a days are searching,, not just kids, alot of people are.
Hopefully it is just a medical issue to get treatment for.
Hope you get good results with the doctor like the others said.. thats the first step..
OtoHNS_MD is right, if he has hit his head, you'd worry about a cerebrospinal fluid leak.
In any case, it's been running for months, go see your doc, that's not normal...
Has he had any head trauma?
If he has tried prescription nose sprays without help, he should definitely
see an Otolaryngologist. If it is truly non-stop, we occasionally will see brain fluid leak from the nose, even without any history of trauma.
ask your doctor about allergies
nasal steroids can help
over the counter nasal saline rinses help too