Sorry, I meant to reply again last night but I was typing from my phone and it wasn't posting!
It is not strange at all for a baby who was previously sleeping longer stretches to start waking more around this age (or for any age that matter, they are always changing!). In addition to the 4 month growth spurt, there are also lots of developmental factors at play. Babies are becoming more alert and aware, and less sleepy. Developmental leaps often affect sleep. Also it is not uncommon for many babies to start teething this early, which could be a factor to consider as well when baby is waking more often.
I would suspect your LO is waking more due to a growth spurt, especially if he is waking hungry at night. There are really two approaches here: You could settle with a feed for now but know that has the potential to create a habit for night waking, or you could resettle without a feed using ssh/pat and/or pick up put down (or if you are like me and are not opposed to a little bit of APing, you could hold or rock your LO, again with risk of creating a prop but a small risk IMO). If you choose to resettle without a feed it is likely your LO will go back to sleeping longer or even all night much quicker after the growth spurt is over. It takes longer to break a feeding habit. However, I really feel that if your baby is hungry, especially during a growth spurt, you should feed him. Feeding more frequently during growth spurts will ensure your supply grows to meet his needs. Your milk supply could be affecting if you are going a long time without feeding him as your body will produce less milk.
With regards to your routine, at this age many babies will start to transition to more of a 4 hour routine. He may not be able to jump to 4 hrs between feeds right away, it's often something you have to work up to. But if you are feeding him too often during the day, there is the possibility that he is not taking full feeds and therefore is not getting enough calories during the day to sustain him at night. By stretching his feeds to 3.5 and eventually 4 hrs he will feed better during the day and will need less at night.
IMO it is much more normal for a 4 month baby to be waking once, twice or even three times a night, than it is for a baby to be sleeping all night long. The main thing is how you feel about getting up that often. If having him sleep longer stretches or even all night long is a priority for you, then sleep training and resettling without feeds may help achieve that goal quicker. I would like my DD to sleep longer at night and I know I have to stop feeding her so much to do this, but I also know that it's easy for me and her if I feed her, and I'm not ready to tackle it yet so I think I will wait until the is a little bit older before trying to get her to sttn, maybe when she is 6mos.
