Knee pain back :(

I had 15 days off from work (my job is very physical - 8/9 hours on my feet, walking around, sometimes need to squat) and I had no more pain at rest and barely any after a 2 hour walk(mild pain would go away after 30 mins of rest or so). 

I went back back to work today and the pain is back. It’s not super bad, but it’s there and I also have really bad pain behind my left knee which I’ve never had before and it hurts when I press there as well. Have no idea what it could be.

I’ve had blood test and X-ray and everything was fine so I’m waiting to get an MRI ☹️

Hi Marie 

Have you had a knee replacement I don’t think you ever said ?

Debbie 

Hi! No. I don’t even know what’s wrong with my knees yet.

Got my appointment two weeks from now. The pain I was talking about behind my knee http://i63.tinypic.com/2l9qhsi.jpg

As I said, it hurts especially when I press as if I had a bruise but I don’t. Any ideas what it could be?