My daughter runs to the bathroom after every single meal and most times passes very small stools what can the problem be? Thanks in advance

Gastrocolic reflex. Babies have a gastrocolic reflex - when food hits the stomach there is a signal sent to the colon to empty. This persists in some people and is not generally a problem unless there is diarrhea, incontinence or other significant stool abnormality.
Bowel movements. We all have a reflex called the gastrocolic reflex that causes us to defecate after a meal, especially a large meal. This is a defense mechanism for the body to rid itself of waste so we could be ready to fight of flee back in the days of old. This is more pronounced in some people and after going through stressors.