Corn and bananas are both foods which can cause consitpation. Myles was prone to constipation so he could never eat bananas, and I never tried corn because I knew it constipate him.
I’d just try some natural remedies and since this is diet related it should correct itself pretty quickly. I’d give him some prunes or prune juice by spoon or syringe if he won’t take a bottle and/or some Benefiber. Benefiber works very well for Myles. I used to give him 1/4 of a teaspoon. You can dissolve it in some water and give it to him by syringe, but I’d do it right before you nurse him because it’s supposed to be given with a fair amount of fluid.
Mylanta never worked for Myles (for constipation).