Not eating solid food

My boy is turning 15 months in a few days, for the past 1 month, he suddenly stop wanting to eat solid food. He use to be able to finish a bowl of Porridge, now he does not even want to have it after 2 to 3 spoons. We tried putting other solid food for him to pick and eat. He is also not interested. Me and my wife are so stressed up. Worry that he is taking in sufficient nutrients. Any advise or expert that we can consult to see if there is any problem. Greatly appreciate any advise.