Our DS stopped eating as much at feedings around 2.5-3 mo. First, we tried the next stage nipples (helped for 2-3 days), various teething meds (was showing teething symptoms), finally had to move to 4 hr EASY, as he just would not eat until 4 hrs from last feed.
The past few days, he's been doing it again. Yesterday, he only ate 22oz in 8 feeding attempts, versus his usual 30-33oz in 5 feedings. We're hoping it's just due to the currently horrible hot/humid weather we're having. We stay indoors, in a/c, but maybe he still notices? As long as he acts fairly normally, and has normal energy levels and responses, we try not to worry too much, although it can be incredibly frustrating to offer him a 7 oz bottle and only have him eat 2-3 oz!