Why Does My 3 Month Old Shih Tzu Keep Throwing Up White Foam?he Wont Drink Water And Is Very Tired?sometimes Will Get Up To Go Pee But Thats It?im Scared! He Got Parvol?

He could be stressed or tensed. How long had you had him? If he is new to his new place, there's a possibility that he might be just stressed on the new home. If this is not the case, he might just eaten something that he keeps on puking out fluids.
 
If he poo with blood.. Possibility that there is parvo is there. Better consult your vet ASAP.