Yestarday, my dentist replaced my old filling with new one and now my tooth hurts and it is super sensitive when I eat chew food on it. What can I do?

Take it easy... Don't stress the tooth; try not to chew on it for a while. Avoid very hot or cold foods and drinks. The filling is probably deep and the nerve is inflamed. This usually resolves on its own, but feel free to contact your dentist for further guidance.