Re: is it thrush? won't latch during day, but fine at night.
Does he have white patches in his mouth or a red rash on his bum? If not, I would say it is a phase. I had a horrid time with DS4 latching during the day. At night he was fine. I started laying down when I could during the day. It helped. He simply was more comfortable that way. We also had reflux and poop issues here with colic. We used a bit of Mirilax for pooping issues which moved the gas out of his intestines which caused the colic. We also had zantac for the reflux. Colic calm worked well as well.