I Am A 45 Year Old Overweight Female...bmi 42%....have Never

I am a 45 year old overweight female...bmi 42%....have never had any knee problems other than some crackling sounds while walking up and down stairs. I have worn high heels everyday at work and have never had an issue. In April, I ended up running about 1/2 block to my car to get out of the rain. I then proceeded to walk about 4 blocks all while in my heels. Something I don't normally do. A few days later, my knees began to feel tight and then pain set in on the front of my knees. About a week later, the swelling began and since that time, I am no longer able to walk normally up or down stairs, I have constant swelling, pressure and pain. I have had two sets of xrays that show some arthritis. My doctor does not think there was an injury and that it's simply arthritis. I do not agree...I understand that my weight is a factor, but up until i ran in my heels, I never had a problem. Thank you