My son is 3 years old, he doesn't eat anything, we use hungry syrup, but no change, we are worrying about him, please give me a best suggestion for him, and one more thing he is always crying, what is the reason for crying?

It seems the problem is 1) food or feeding is a punishment to him, 2) whatever he wants he gets by crying. So now remedy is give him enough time to eat but no choice. Let him cry and console himself to get over the habit of crying. Once he knows that crying will not yield anything, he will be different. It seems he is very sharp, intelligent child. So try these gor a week or two without a break and provide me feedback. No medication please but for deworming medicine every four months.