Food issue. Hungry. he is very active.

Hi doctor, my son is now 18 months. He is little under weight. When we visited doctor, she prescribed Orovit 5ml and Laktrum 1 spoon in the bottle daily (5 months before). His main problem is he can't eat solid food. He will chew but can't swallow. Hence we are giving grinding food. Semi solid. Food is finger millet mixed with all pulses and rice, dal and vegetables. Past 2 days he is not at all eating properly. We tried a lot but not. He don't want to eat idli, dosa roti puri not even biscuit or fruits ( cut piece or puree) and 3 times milk in a day. How long it will take him to have normal chewing and swallowing food. Any medicine that makes him hungr buny. We have not visited doctor because of current situation. Please suggest me for his weight gain and feel hungry. He is very active. Thank you for your valuable service.