what could be causing my sons diarrhoea?

so my son is 4 years old, and today alone has had 8 bowel movements, that are like water ( he is not potty trained, a medical issue we are currently working on with his paediatrician) yesterday and the day before he had about 6 bowel movements but they weren't as running, they were loose but not as bad. ( he normally has 1 a day) he has NO fever, isn't acting sick, and says his tummy doesn't hurt! he is not a big eater as it is, so i haven't really noticed that. im just unsure if this is something i should take him to the clinic tomorrow? seeing how its not going away, or if its probably just a virus that has to pass through?

just a little not where i live we cant just call our dr. you can make an appointment usually 2 weeks from the time you call, or you go in as a walk in and wait any where from 6 -8 hours depending on the day.