Tore acl 3 years ago. since then always had tightness in hamstrings. twisted my knee few days back and hamstrings hurt but healed. knee feels loose?

Review with your doc: If you notice any instability particularly with squatting, rotating, or walking down stairs there is a possibility that something happened to your repaired ACL. This may be particularly the case if your knee is swollen - suggesting some sort of inflammation in the joint. This is something that your orthopedic surgeon may want to know about.