My 5 Year Old Just Bit A Double A Battery.

My 5 year old just bit a double a battery. One of his k9s punctured it. He had some black stuff in his mouth i had him garggle several times and spit it out and i wiped the rest out with paper towles and qtips. The tip of his tounge has what i think is a small burn. I read on another site he should drink some milk so i gave him some. Other than the small burn he seems ok. Is there anything else i should do?