2 year old constantly gets diarrhea and stomach pain and low grade fevers what could it be??

Diarrhea and Fever. Recurrent episodes of diarrhea, stomach pain and fever in a toddler are of concern because these symptoms point to an infection or inflammation within the gastrointestinal tract. The fact that your toddler "constantly" has these symptoms is also concerning because this indicates that this is not a self-limited illness. Your child should see his Pediatrician very soon for diagnoses and treatment.
Chronic diarrhea. Your child could have a food allergy or food intolerance. Also check him out for celiac disease. A third possibility is juice which contains fructose or sucrose which can cause diarrhea.