HELP! Kitten with diarrhea?

Ok I just got my kitten Saturday and it has been doing fine, until last night, MOnday. It had diarrhea. Until then it had only 2 but hard stools. We have been feeding it cow's milk so maybe that's the problem? I t can't have parasites since it just started to have diarreah and the vet said that a little salt in the food can prevent that. I gave it some chiken and rice. It is still playfull but today it again had dirrhea,Tuesday around 4. It was very watery, and he meow's when he pees. I don't want to go to the vet yet, because it is alot of money, especially if nothing could be serious.... Please help me, tips advice anything. The kitten is almost 6 weeks old and won't eat dry food..WHAT SHOULD I DO?