Sudden knee pain

Veil5577

I'm sure someone here has had this problem so I'll ask here. Today, after working with my laptop on my lap most of the day, I noticed severe pain in my left knee when I straighten or try to stand or walk on it. I didn't injure the knee or bang it that I know of. For a long time I've noticed creaking in both knees but I put that down to getting old. This came out of nowhere today. Anyone know what this might be? In addition to the pain in both my ankles from Achilles' tendinitis and the back surgery I've had, I have so many musculoskeletal problems that I'm beginning to wish I could trade them in for a mild heart attack. The worst of it is I can't afford to go to the doctor, even with insurance because I still have to pay out of pocket for a portion of it, and well, my pockets are empty.