I work for Amazon.com. I am an order picker which requires me to walk 15 to 20 miles a night. In the middle of my 4th night I started to have knee pain in both knees but I finished the night. After work I found it very hard to walk. I can not bend my knees without pain. I can walk as long as I don't bend my knees. They are swollen next to the kneecap on the inside of my knees. Both knees. They are red and warm to the touch. Should I see a doctor?