Hi team, sending this on behalf of my wife since she doesn't have a account:

She first hurt her left knee hurt about 7 weeks ago by squatting down to tie our daughter’s shoe, way past parallel, felt something stretch/tear down the front of the knee and it hurt a lot. Stood up and bent/stretched it out and the pain subsided in less than 5 minutes and was able to walk immediately no problem. A few days later did squats and deadlifts, no problem.
A few days after that; she did deadlifts and then push press, during push press it happened again and hurt so bad she couldn’t complete the work out it was a sharp intense pain. In a few hours she did air squats without pain. A few days after that she worked out again without issue.

But randomly she started getting these shooting sharp pains when approaching parallel just sitting down in a chair. She hasn't tried to work out since because of the fear of pain.
A few days ago we went snowboarding and she was able to snowboard no problem, but when she sat down on the floor to put the board on, she had the sharp pain again, she was still able to snowboard down the mountain only having pain when falling with her knee bent.

There is no swelling or bruising. No weakness or instability. No issues with stairs or walking. It will feel perfectly fine having stood up and sat down dozens of times in a day, and then all of a sudden it happens. We are not able to find anything on the internet that describes the symptoms. She hasn't seen a doctor because the pain has been so random, but now it is starting to manifest itself more often.

She's afraid of getting numerous and expensive tests to diagnose this and in the end, not getting results. We are wondering if anyone has heard of this before and how to diagnose/treat it or at least where to go for help.