I can't afford a picky eater

I'm beyond frustrated and disappointed in myself. We are expecting a second baby in March and unfortunately our income fell into a crises during our move because we in countered  big unexpected expenses that our " just in case" set aside money didn't cover. So now I don't have the money to make 2 or 3 different meals for each meal. As it is we buy pediasure drinks weekly, fruits and veggies weekly that end up going bad because he won't eat them or he will spit them out. he gets vitamins daily and a pediasure drink daily but he's still at 25 pounds and has been for the last 5 months. His 2 doctors said  he's got no medical issue that would cause him not to eat and all of his symptoms are just him being a picky eater. And it's just a phase and bla bla bla. We're switching to a new pediatrician ,tomorrow  is the first appointment because I feel like the doctors arnt taking this situation serious enough I don't know what else to do  When my baby boys stomach is growling and I can't get him to eat anything unless it's sweets 😩