Suggest regular formula (no iron) for a week and see how his stool movements are. If they return to normal then it is the iron in the formula. If not, then there may be an issue that the doctor has to help you with. Do not recommend corn syrup. If you are worried about anemia, ask your Doctor about low dose liquid iron supplement for infants.
Yes and I mentioned that to the doctor as I'd heard from some sources that iron can be constipating and from others that this is not so. He said that too much iron can cause constipation but that the levels in the brand I'm using should not cause a big problem and that iron is necessary for my son's nutritional needs. I would be concerned also about limiting iron too much or giving him a formula without it because I know when I was a baby, my mother told me that I became anemic and had to have iron supplements until I got on solid foods. I didn't have this issue with either of my other children (constipation or anemia) but I know every child is different.
Does the formula have Iron in it?
I forgot to add that we tried switching his formula from regular to the gentle with whey proteins but that didn't make any difference at all after two weeks and he didn't seem to like the taste as much so we switched back to the regular stuff.