I've not an advice, but I can share my experience.
I had a similar issue with my LO when he was 3.5 months. He was starting eating at the breast and after few minutes he refused it (sometime, but not always, he did want the second breast for a while, or took some breastmilk in a bottle). At that time, I was feeding every 3-3.5 hours, but often he did not ask to be fed (he was discovering the world around him and he was very distracted). Moreover, he seemed much hungrier than usual at night. I tried feeding in the dark, and it helped a lot, since he was much less distracted by things around him (this is the reason of why he ate better at night). In addition, I went feeding every 4 hours: in this way, my breast was much more full of milk and my lo was hungrier and ate better. Four months is the time to switch to 4h-easy..