Hand cramps?

My mom has arthritis in her spine and hands. When I was 6/8 years old my mom said my legs kept giving up and I would collapse a lot. Hospital said most likely arthritis however I was too young.

For the past 6-9 months, whenever I do activity involving my hands; eg- washing up, hoovering, on a phone call, writing etc, my hands will hurt after 2/3 minutes and then they will cramp and stiffen/lock in place for a few minutes, sometimes they get a little swollen.

This morning I did my son some breakfast and it was hard to even hold the box of cereal, I’m very weak almost everyday especially in my hands but also my whole body. I eat 3 meals a day. I also take vitamins.

I’ve called my GP twice, blood test was negative for Rheumatoid Arthritis.

Any idea what it could be?