M.T.
My daughter was bottle fed and I had the hardest time get her into a nap schedule also. Baybies need to be trained on how to sleep...I know I thought that it was strange too. There could be a couple reasons for why this is happening. It very well could just be a phase...all babies go through sleep phases. I think my daughter had a new sleep schedule every other month. Just when I got the hang of it she would change again. Another reason could be that he is going through a growth spurt and just needs to eat more. Maybe talk to your Dr. able possibly adding a small amount of cereal to his diet. Or maybe he just is ready for more awake time which might mean longer tummy time and a little more vigurous play when awake. I went through the same thing and was ready to pull my hair out but I just kept to it and by the time she was about five months old she finally started taking regular naps. He will keep changing his nap schedule until he goes to one nap a day so don't loose hope.