Odd sensations on interior side of right knee, what could it be?

I’ve been having odd sensations like my knee is catching and tingling or locking and feelings of instability in my right knee for a couple weeks. Then, I started running again yesterday, not thinking much of it, and I am having stronger pain on the interior of my right knee than my left knee. I have been having balance issues all day and my knee has been locking. Is this something be concerned about? What could it be?