Does it hurt walking up stairs too?
My knees also hurt after two babies, did accupunture, no help.
Went to see a Chinese 推摩 master, he checked me over & said it was my pelvice hadn't close up properly after deliveries. This apparently affects the knees. Anyway after one treatment & a few months later (the pain didn't go away straight away), my knees don't hurt anymore.
If you have tried everything with no help, try looking into this area.