In reply to masshuu:
I don't want to put you on a massive downer, but;
One thing to bear in the back of your mind, hopefully to be banished by a diagnosis, is OCD. Mrs D had not dissimilar symtoms in August, a week after a great trip to the Alps, and it took a senior knee surgeon to look at her MRI imaging and diagnose Osteochondritus Dissecans (OCD). This is the big daddy of all knee problems and makes you write to Santa for a meniscus tear. It is really unpleasant, the bone at the end of the femur dies and the stressed areas can shear off with repeated microtrauma, so it manifests itself in the sporty and active (she ran 3 to 5 times per week for 30 years) which makes it particularly cruel.
She had an operation to pin the detached piece back with 5 screws, but it does not seem to have worked. She hasn't walked unaided by crutches since and faces another op to graft bone onto the fracture. Climbing and walking in the hills are unlikely to happen anytime soon, though long term there seems to be hope that it is possible.
Thats the bad news, we were told by everyone from A&E upwards that it was probably a meniscus tear and spent several weeks making it worse on that basis. The good news is that this is very rare condition, you have an approx 20 in 100,000 chance of it being you. Outcomes are improved by rapid diagnosis and surgery, which is why I post this, if you are this unfortunate, the clock is ticking and the detached fragment is dying.
Post edited at 19:18