good news is that if you build it up, you will grow out of it. try to relax and not grip the violin too hard.
i have been playing for many years and i still get cramps in my left hand every so often. it's usually the result of gripping the violin too hard while trying to position your fingers, when it happens i stop playing for a few minutes and then when i start playing again i focus on relaxing my grip on the neck of the violin. it also tends to happen more when i don't play for a few days. if i play regularly it tends not to 