Hope you are not in too much pain. Symptoms suggest lateral meniscus injury. Closed chain exercises like squatting and climbing stairs must be avoided. A physiotherapist can clinically diagnose it's grade. If it's higher then you've to go to an ortho surgeon. Lower grade injuries can be managed conservatively by physiotherapist based on his assessment. Manual unlocking procedure can greatly reduce your symptoms which will be taught by the physio. Ice packs can help reduce inflammation. Knee Braces can help you to be mobile, which may be suggested by the physio.
Get a xray knee done and take a orthopedician's opinion on it.
Take a tab. Aceclofenac and paracetamol combination twice a day for three days.
If you have had any trauma, then you shouldn't wait to consult a orthopedician.