I am a softball player and sometimes after tournaments i get an intense pain in between my thumb and pointer finger that lasts about a week?

Poss ligament injury: Repeated painful stress of the ligaments at the base of the thumb can lead to chronic instability and later arthritis. See also: http://jbjs.org/content/50/3/439 Small fractures at the thumb base can also occur so x rays are often done. Classically these fxs. happened to pigeon breeders when they strangled bad pigeons, so they were named pigeon breeder fractures (now known as Bennett fxs.)