I Am A 24 Year Old Female, So Ive Been

I am a 24 year old female, So Ive been waking up with stiff/sore hands for the last three weeks... When I wake up I find it hard to straighten my fingers. If I run my hands under hot water the pain/ stiffeness goes away, the pain in my right thumb( in the mcp joint) in particular is consistent throughout the day. Sometimes my thumb hyper extends an is very painful. In cold weather my hands tend to seize up. I am not experiencing pain in any other joints in my body. I have tried to increase magnesium intake through diet but it has not worked. Any help/advice would be appreciated. Thanks