15 months old not eating at all. Issues?

My baby boy has always been a poor eater and not able to chew any textured foods hence I end up giving him pureed foods. Somedays he might eat mashed foods but those are rare 1 or 2 days in a month. Additionally, he is not able to drink from age appropriate bottle and he drinks milk from bottle recommend for 0-3 months. I had tried faster flow teats but of no success. Could this be a behavioural issue or some throat related issues? For past 10 days he stopped eating solids.. during 24 hours period, he might take quantity of like 1 biscuit and nothing. He was earlier taking 3 small meals + 1 snack but now nothing . I have been trying varities and textured finger foods which he will take a bite and spit it out immediately. I am clueless now on what should I do to make him eat anything.