My son had knee pain for 3 weeks during dr. exam pain was so bad he almost vomited. 1 hour later pain free and full mobility. he did take a naproxen?

Glad he's better: It is too soon to tell if pain relief is from the Naproxen or whether the problem causing the pain was solved by the manipulation during the exam, hopefully the latter. It would be helpful to know what his doctor's diagnosis was and what recommendations were made. If pain recurs, I recommend rest, cold compresses, and continue a few days of Naproxen until inflammation or injury heals.