DON'T FEED PEAS THESE ARE CARNIVOROUS FISH AND THAT WILL KILL HIM.
Also babies need to be in at least 2.5 gallon tanks with a temp of 84+, anything under that is too cold for a baby betta. Also you need to feed babies brine shrimp and you should NEVER stop feeding a baby that long, they need to eat every day three times a day to help them grow. I would say bump the tank temp to 85, do a small aquarium salt treatment as well. Chances are at this rate though the baby won't survive. They are very hard to keep alive unless you know what you are doing.