Knee Pain

Are you stretching before and after your rides? Takes less than 5 min and can make a big difference. You just need to do three strethches; quad's, calves and hamstrings. Also have you tried a neoprene knee support/tubegrip? One of those can help loads too.

I agree, doctors are crap. I have long term back injury, when i first did it doctor told me to take some pain killers and it would go in a few days - still have the problem 2 yrs later

doctors aren't crap.
you just have a crap doctor.
find a good doctor who will give you a referral to a specialist and get it looked at.