Our son has experienced some sleep training... regression. I don't think that's the right word for it given the circumstances, but here goes.

We started sleep training with him when he was 7 or 8 months old. We got him to where he would sleep through the night more often than not with occasional waking in the wee hours of the morning. 

Now he has been teething for about 4-6 weeks. He has one tooth close to fully grown and another that has (finally) broken through the gum-line on the bottom. I can see and feel his top two teeth coming in on the top as well. 

Now at 10 months, he is waking up in the middle of the night, every night without fail, to nurse. And he is most assuredly eating and not just comfort-nursing.

Has the middle-of-the-night nursing blown away any semblance of the sleep training we did, and how difficult is it going to be to break him of this habit?

I will be back to update if any breakthroughs occur :)

**EDIT**

We have a very normal and predictable bed time routine in place. 7 PM nurse, change the diaper, get in pajamas, read a story, sing songs, down for bed at around 8 PM. 

**Update** 

We came home from a long weekend out of town and he got sick (we think). He has(had) a VERY runny nose with clear discharge. This weekend was highlighted by short naps (if any) and waking in the middle of the night with nothing to comfort him. He refused the breast, a bottle, being held, and rocking in the chair. After half an hour of sleep training (Ferber style), we brought him to bed and he finally nursed himself to sleep. 

The problem (most likely) is pain from teething that is waking him up. His front two teeth are causing the problem currently. One has completely cut through the gum line, and the other is still working its way. I think the tooth should be all the way through today. 

**Update #2**

For the last two nights I have gotten up with him (thanks @Aparente001!) and given him a bottle. The first night was awful... he wanted mommy something fierce. Last night was a bit easier. I rocked him and patted him and he fully calmed down. I thought about trying to get him to go back to sleep, but he gave me the impression that he wasn't going to have any of that. After he put down a 5oz bottle (glad I gave it to him) I laid him back in his crib and he went directly back to sleep. This may be a "wait-it-out" kind of situation (thanks @Ciacciu!)

**Update #3**
My wife and I *both* got a full night's sleep last night! I have a feeling he wanted mommy when he woke up, but after two nights of getting daddy he figured it was just easier to sleep. Here's hoping this is the new pattern.