So a few weeks ago Ds started drinking more.. 6oz from 4oz every 4 hours so 8am, 1230pm, 4pm, 8pm, and night feeding 230am.. Give or take 15 mins and just the last few days he is not interested in a bottle when he wakes so around 9am he will have a bottle but seems so not interested, it either takes him forever, he spits it out, or just plays with the nipple with his tongue and only drinks like 3.5oz and won't even want another bottle for 3.5-4 hours and that only he only takes like 5oz but for the other 3 he drinks the 6oz. Should I be worried? Why wouldn't he be drinking as much? Thanks!