5month baby lack of appetite

Hello dear community.

I am a bit puzzled. My 5 month old son suddenly consumed less than 500-600ml per day while I was used of 800-900ml. It has been 5 days he continues like that. He mostly doesn't eat during day. He is a bit more cranky and want to be hold. When trying to feed him, he cries. No fever, no other symptoms except he shows no appetite.

I would have already taken to pediatric but i am in China. To see any doctors, only hospital is available choice.

Does anyone had a similar pattern of low appetite?