My 4 month old spits up a lot and poops 4x a day. his temp is 98.2 f but his head feels hot. this started 4 days ago. formula fed. maybe teething?

Is this a change: A lot of 4mo spit a lot & many poop that often. Babies lose a lot of body heat from their head so a warm head isn't particularly worrisome.Having a normal temperature is good, but doesn't rule out the early stage of a new illness. If this is a change in your babies pattern it points to some form of stress & may take a little longer to show clear signs.

Maybe not: Teeth start to erupt around 5 to 6 months. This sounds too early. Maybe consult a physician. With teething they usually act very fussy too.