Your history and symptoms, are suggestive of a ligament injury
within the knee joint. You need to be examined and probably a MRI
needs to be done.
If it is a Ligamental tear, depending on the severity and the type of ligament injured, you may be need simple painkillers and rest for few weeks with limited activity.
If there is severe damage, with free ligament fragments within the joint, they need to be removed with a minor surgical procedure (arthroscopy
If not treated, properly this condition persists as a long term painful condition, with inability to resume normal activities.
Hope this helps.