Spitting up and having trouble eating

Da

My son is 5 months on the 24th for formula fed on similac advance and he has been on some rice cereal and some other level one solid foods for about a month now he has recently started spitting up and burping a lot and giving me a hard time during bottle feedings and is spitting up a lot this is all new I’m wondering if I need to contact his doctor because he’s not eating as much as his normal amount