Baby not eating

Hi my baby 13mo has not been eating. Not a single solid food. It has been 4 days now. I find it weird because he’s normally not like this. He was a very big eater. It was very sudden change after i picked him up from ifc the other day. He’s still drinking fm tho but not a lot also. Sometimes he sees us eating and will approach and look. But when we offer food he turn away and cry. Is this just a phase or Should i bring him to see a doc?