Hi, I've just had my second bout of arthroscopy on the same troublesome knee, first was in 2005. I'm now ready to run on a treadmill after 6 weeks of physio exercises, I felt ready to go a couple of weeks ago but psychologically struggled to get out there!
As Cookay says, get to the doctor, ask for an MRI straight away rather than potentially wasting time with a period of physio that may result in a referral for an MRI anyway.