gagging on fingers

It`smeC

My son is 13 months old, and is constantly chewing on his fingers, but he puts them so far in his mouth he starts gagging, and heaving, and it has led to throwing up a couple times. The thing is, he never stops, I have to pull his hand away, but he does it alot in the car where I can't reach him while driving. Anyone been through this? Any Suggestions?