I'm so sorry Janet I hope everything works out! I know I'm the young one around here
but I know the pain too... I had arthritis in my hip when I was 6 years old. It seemed to just come around overnight, and in the morning I got out of bed, stood up, and started screaming and bawling because I was in too much pain to move. Luckily I grew out of it but I'm not in the clear, because the doctors told me it would likely come back at some point. Joint problems run in my family too. My grandma actually just had a knee replacement last week after a couple years of pain. She's bed-ridden for now but feeling much better for going through with it.
I hope whatever is hurting your knee isn't too serious!