There is a really weird multi colored spot under my thumb but i'm really scared to go to the doctor. will my blood be taken for results?

Doubt it.: Multicolor is unusual and makes me suspicious for a resolving bruise. A simple look should suffice to identify this. A bruise should resolve with time. If this is not resolving I think your doc should look at it. I do not suspect that drawing blood would be helpful.

Typically colored: spots require possible biopsy not blood test. I would go see dermatologist. The sooner you find out what it is and how to treat it, the safer it is. And you should feel very little because we numb it up! Be safe, get it checked!