Both my kids (daughter was a soccer player) were prescribed meloxicam. Both said it didn't seem to help--although I'm not sure they gave it the full 14 days.
(You probably already know that) meloxicam is an NSAID, like ibuprofen and naproxen. My kids preferred taking ibuprofen. You might ask your doctor if your son can take a higher-than-OTC dose of ibuprofen for a few weeks. The prescription version of ibuprofen amounts to 4 OTC pills per dose, if I recall correctly. I had shoulder surgery not long ago, and that was what my surgeon recommended for pain.
My daughter's orthopedist also recommended arnica cream as a topical. She didn't seem to think it helped much, but she did use it. It's nonprescription.