I feel you on this one, it's super stressful when they suddenly refuse the bottle! Have you checked with your PD just to rule out any mouth soreness or reflux that might not be obvious, since sometimes babies reject bottles for reasons we can't see? In the meantime, a few of us mums found that warming the bottle slightly or even just changing the teat size (sometimes they outgrow one size without us realizing) made a difference, and honestly some babies are just stubborn about certain bottles so it might take trial and error. Since he's managing the straw and spoon, he's actually doing better than you think, but do get the PD's take on whether this needs intervention or if it'll pass on its own. At his age it's definitely not about weaning yet, so don't worry about that part.