Hi there,
Sorry your LO isn't feeling so great.

When you say every morning he has explosive poohs - how long has that been going on?
THe fact is that lots of LOs have some strange stools when being introduced to cow's milk, it's a hard protein to digest, but if this has been going on for a while and it appears he is in pain at night with abdominal/digestion issues it is very possible he may have an intolerance/sensitivity or allergy.
Is there any mucous in the stool? Red/black specks? (that can indicate blood).
Ask your ped if you can bring a stool sample (I would just wrap up the dirty diaper in a plastic bag and bring it in) to be tested for microscopic blood. Or just bring it in - it's a very quick test they should be able to do in office.
How is he doing now? Big big (((Hugs))).