M.R.
Our son is 6 months and he has his good days and his bad days, but we have accepted that the light at the end of the tunnel will be here soon and most importantly we are remaining consistent in our techniques for sleeping.
Our nighttime sleep is pretty good - only wakes once or not at all during a 12 hour period. The issue we're facing, however, is many of his naps during the day are only 45-60 minutes. He wants to take one super early, one in the mid-morning, and then we just pray that he'll take a big one in the afternoon. When he doesn't get into that restorative sleep phase, he's an absolute crab and unbearable.
Despite all of this, we still do the same, consistent wind down and soothing routine. We still put him down for naps when he shows telltale signs of readiness with the hopes that he will take a good, restorative nap. If he does, great...but if he doesn't, we just try again at the next nap opportunity. We are resigned to the fact that as long as we remain consistent in our approaches, he'll eventually be fine. And we ACCEPT that as how our baby is going to sleep for now.
How much does your baby weigh? Does he have a true *need* to feed in the middle of the night or is it a soothing/want? You need to decide what it is and how you want to approach it. No matter what you decide, however, keep it consistent. If you're going to go in and nurse him then expect the behavior to potentially continue with the wakings (I'm definitely not saying you're doing anything wrong; I'm merely saying that he has learned that when he wakes and cries for you, he knows you'll come and feed him so he will continue to call out for you when he can't go back to sleep).
You may be at the point where you have to, once and for all, decide how to approach this. Do you want him to sleep through the night? If so, you will need to make changes in order for this to happen. Do you reject all forms of CIO and refuse to do it? If so, you will need to wait until he decides he doesn't want to nurse/soothe from you in the middle of the night. Either way is fine - you just have to be comfortable with your decision.