I Have Severe Pain In The Back Of My Knees

I have severe pain in the back of my knees and they are swollen. I also have pain in my calves and they are swollen as well as my ankles. I can not walk without pain especially going up and down stairs. there seems to be knots when I touch my calves and it hurts to the touch. I looked up bakers cyst and also knee replacement. I have a lot of symptoms for bakers cyst. I am a 70 year old female that is the only caregiver for my husband who has alzheimers. Could this be caused from being a nervous wreck most of the time? thanks for any advice you have to offer.