Good evening. I have significant swelling on the inside of my right knee and severe pain on the left inside back of my knee. If I feel back there it appears to be a very thin muscle or tendon. I am wondering if this is a meniscus tear or something else. I cannot walk on it or straighten out my knee. I have recently moved and have been working really hard to get the new house all set up and one room repainted, utilizing an extension ladder. I was extremely sore, working 18 hours a day, however today, all of a sudden the above symptoms appeared.