Knee Injury Question

I experienced what I think might be a MCL injury but not really sure. I have pain / tenderness inside my left knee.
When I attempt to climb or left my leg up something is moving or snapping from my the inside of my knee
up toward my leg (it is visible). There is tenderness but no swelling and I am still able to workout. Any idea? Has anyone experienced this?

Thanks

Climber /PT here - any specific moment of injury?  most likely a tendon issue (medial hamstring or adductor 

I have/had similar symptoms.  I was doing an approach with crampons this winter, planted one foot, to step over a log, and as I twisted, felt a pop on the inside of my knee.  Thought it was a full tear feeling the pop.  Fortunately, just a mild sprain of my MCL.  Just been resting it, and taking it easy, staying off the ice, and just normal walking.  

Without a doctor's visit, it's going to be hard to diagnose.    

I would reccomend seeing a good chiropractor. Has helped me and can diagnose/treat for considerably less than a hospital visit. Mine would pop or give out randomly. Ended up being out of place caused by an ankle issue.

Am so sorry for your injure I will suggesting you find a good chiropractor.