Sick toddler only eating pouches

Hey I hope this isn’t off topic but my old April and March 2019 boards are super slow and I need advice.

My 18 month old has been teething bad all week with a low appetite, and then yesterday had a high fever and a horrible constipated poop. Today his fever is gone, but yesterday and today he has not been eating ANYTHING. I have offered him all his favorites but he is rejecting solids. He had only eaten breast milk, chocolate milk, juice, and fruit pouches. It’s the only thing I can get him to eat that is food. I think he’s sick - no cold symptoms yet but that fever was probably the start. Is it ok to let him eat these pouches? Should I call the nurse line?