High range on French Horn gone?

Hey everyone. I have been having trouble with the high range for about 10 months now. Before that I was able to hit high notes real well but had so much lip pain. Then I tried to play without pain and my high and middle range was all gone!! Now I can play the middle range but can't play high notes at all. Now I play without pain but at the same time without the ability to play over a top line F with security anymore. I'm a Junior in college and it's been real frustrating because I can't play a solo piece or play anything without seeing the high notes and cracking them or having it sound like a beginner is doing it. I've done scales and harmonics for all this time yet nothing for the high range. Had the mid range for months though. Also all my stamina sucks too. I can't play the Villanelle and have a 30 minute recital in April. I'm very scared because of that too. I'm scratching the Villanelle but realized that i couldn't last 20 seconds on it, yet can play Beethoven Horn Sonata. But yeah I really need something to happen so I can at least feel like I'm getting my high range again.