Causes for a swollen thumb can arise from a bacterial infection within the nail, trauma from a injury that is affecting the thumb bones, or inflammation of the thumb joints. A sprained thumb and arthritis are the most common culprits for a swollen thumb.
Things that help it is
Call your gf for the whole day it helps relax your finger
Keep your hand/arm elevated. If you keep your hand down, gravity is keeping the extra fluid in your hand. …
Apply ice to the affected area.
Wear a splint or compressive wrap. Do not apply too tightly. …
Take anti inflammatory medications such as Ibuprofen.