My son will be 3yo in March and seems to have taken a step backwards with regards to eating... he used to eat by himself using cutlery and ate everything what was given to him, but now he only eats if I spoonfeed him and is an extremely fussy eater, even sometimes eating nothing all day! He still drinks from a sippy cup, refusing to drink from a normal cup or bottle, even with a straw! And he does not want try going on the toilet... the times I have tried he goes rigid and cries hysterically! What can I do to help with his development?