Hello, I Have Had Knee Pain For Several Years That

Hello, I have had knee pain for several years that has gotten progressively worse. I've been "diagnosed" with arthritis then told I don't really have much arthritis. I recently was "diagnosed" with IT band syndrome. However, the IT band stretches offer no relief whatsoever. I've seen several orthopedic Doctors and seen by my PCP about my knee pain many times. I have periods where I feel like there is cool liquid running down my leg from my thigh to just above my big toe. When I participate in aerobic activities, I have severe knee and foot/ankle pain with tingling sensation in my toes. The best way I can describe it is that I feels like something in my knee is going to snap inside my knee! I have deep ache/pain in the back of my knee on the left and pain on the front (right) inside. I also have deep ache in my thigh. At times, the only thing that helps is if press my thigh extremely hard or press deep into the back of my knee. I use the foam roller on my thigh, cans, tennis balls, rolling pins, etc. to press hard into my leg to help with the ache. I am considering going to the ER because I feel like something very bad is going to happen and it frightens me. Any help you can provide would be appreciated. I'm so frustrated with this that it is causing tremendous anxiety. All I can do at times is cry...