Once a good eater, no longer wants anything!

My son used to eat so well, now he just throws everything I give him on the ground for the dog to eat 🤦🏻‍♀️ not sure what to do anymore. He’s barely gained a pound since his 9-month appointment. My doctor doesn’t seem too worried since he is gaining weight and growing, and he’s super active so that could be playing a part in the slow weight gain, but now that he’s getting pickier and pickier by the day, I’m not sure what to do. He’s been feeding himself since 7 months (baby led weaning) and won’t let me feed him except he lets me spoon feed cereal and yogurt so he at least get that. He’s also still breastfed and drinking way more than I’d like but want him to be eating his foods before attempting to wean. Anyone else’s 1-year-old all of a sudden fussy?? Any tips or tricks I may not have thought of to get him to eat better? TIA