GUINEA PIG! REALLY URGENT PLEASE HE CANT DIE PLEASE AS MANY PEOPLE AS POSSIBLE!?

my baby boy guinea pig is 7 weeks old. today right now he had a watery squishy poop. what should i do? should i give him a bath? and i have to leave tonight for three hours so should i stay home and watch him? im really scared i already lost many animals even though i educate so much before i get the animal! please help me! anything will work!!!!