Injured knee, what have I done?

I was cycling up a fairly steep hill a few weeks ago and stupidly took a phone call. I wasn’t really concentrating and was in too high a gear, so was using a lot of forced rather than spinning up and also holding the phone with one hand and wasn’t really in an ideal position.

I had knee pain which came on suddenly in my left knee, I limped home and generally been fine walking but I have to be super careful climbing stairs or I get a bad pain in my knee.

Any ideas what I’ve likely done and how long to recover. Should I try riding again or just keep resting it?