Stomach bug? Something else?

So my 16 month old for the past week and a half now has had super loose stools/diarrhea. Also the worst diaper rashes. He screams in pain from them. He has no other symptoms. Eats fine, drinks water, no complaints. I thought maybe teething? But now I’ve been having stomach issues almost the same for the past week. Could it be something we’re eating? We eat super healthy, almost no processed food, no candy, etc. The only thing I can think that we eat almost everyday is eggs? Idk if it’s a concern enough to call the pediatrician. What do I do??