Hello, I am stuck as to what to do next. Injured my knee approx 4 months ago, had two MRI s and an Ultrasound which shows nothing. The pain is behind my knee, and is worse upon full flexion, and often times feels unstable. I have been on meloxicam for 3-4 weeks with mild relief. I also got a cortizone shot, as well as did a 6 day steroidal dose pill pack. I read about a PCL injury, but wouldn t the MRI have picked that up ?? Please advise/help ???