What's wrong with my knee?

[redfreezy]

Since about the age of 6 I've had issues with my knee (I'm 18 now). My knees (and other joints) have always been pretty flexible. I can bend them into weird shapes. My knees crack every time I stand up. But the real problem is with my right knee. Anywhere from 1-3 times a year my knee will pop out of place. Not sure if it's dislocating or subluxating. Essentially, my patella feels like it's sliding off to the side (lateral) and only returns to its normal position if I straighten my knee or wait a few minutes for it to return by itself. The pain is terrible. This usually happens if I bend my knee a certain way, but I've never experienced serious trauma to the knee. The pain only lasts about 15-30 minutes after the incident and I'm fine afterwards. Recently my knee hasn't been doing this completely. Instead, it pops out and goes right back immediately. I've also been experiencing some very mild knee pain (on random days when my knee hasn't popped out) and a very irritating tightness in the back of my knee. Any ideas? Should I ask my doctor for an x-ray? Thanks in advance.