Talk to Pediatrician on Not Eating Enough

My son is 2 years and 2 months old. He is not eating much these day. We doubt it is due to teething process but his food intake has decreased dramatically and so has his weight. He only takes milk and that too in very little quantity. Previously we gave him maltofer because he used to eat paint and mud, 2ml per day for 40 days. He lost his appetite during these 40 days and he also didn't stop eating paint. We tried to give him pediasure but he didn't like it. Kindly recommend some medicine to increase his diet