Quick question about feeding schedule

Does anyone else's 4-month-old eat like a normal human on some days and then become a ravenous beast the next day? Our son went through like 6 ounces yesterday but today he keeps turning away from the bottle after 2-3 ounces. My wife thinks he's sick but he seems fine otherwise. Growth spurt? Teething early? Just a weird day? Asking for a friend (it's me, I'm freaking out).