In reply to Ed morris:
Hi Ed. I had something similar happen back in early December. I initially ignored it but it didn't seem to be getting any better. My knee kept swelling up/hurting a lot when used and i was walking with a limp.
I had an op about 9 weeks ago to repair a double meniscal tear and it is a lot better now than it was before. I've gone from having a swollen knee that had sharp pains on the inside and outside (and limited range of motion) to being fully able to boulder in roofs again and use heel hooks, toe hooks and fall off on to pads
Did they say that the MRI had shown anything? I don't think they heal themselves unless very minor and although you can probably do a lot of things without aggravating it, I figured it was best to go for an op and remove the tears so there was nothing to catch inside/fold/tear more.
The rehab went well doing some physio exercises as well as lots of stretching/cycling and then easy climbing up and down without jumping off for a few weeks.
Hope you can get it resolved.