Stomach pain.

Hello. I have a 6 year old Autistic son. He struggles with verbal so at times I honestly don't know what's wrong with him when he is sick or something. Twice I rushed him to ER for stomach pain just to find out he had severe constipation. So right now he is pointing at his stomach and when I press hard enough not too hard he cries but if a light press he doesn't really complain. He is an extremely picky eater. I just wanna know if y'all think its just constipation again? I have a younger child(a baby) and nobody to watch him so I don't want to go to ER if it's just constipation again. Is there a link of stomach issues and constipation? Because it happens a lot. Please no judgment for me not wanting to go ER again. My younger one is sleeping and he gets very angry when leave the home. Plus he has a cough and it's cold outside 😔