Left leg is tight
Yesterday I was sitting in class and my entire left leg started to get really tight. When I stood up after class my knee had a sharp pain in it for a few seconds. I don't know why. From my hip and down my whole leg is tight. Especially my quads. At times it isn't bad, and at times it is worse. It feels like I've been given a shot in my hip actually.
I don't know what this is. It is just a sudden onset of tightness. I was able to go into the gym and do my squat workout. I even felt stronger than normal. It's the heaviest weight I've done in a while and it was even easier than last week when I didn't have this problem. Now today, a few times my knee has given me a few more sharp pains, but there wasn't any actual indicator of any of this while I was lifting yesterday. It all disappeared and began to come back.
Any ideas and advice? I've tried stretching it. Maybe it just needs more.