Help please - Sleep training worked then didn't!

[Tortoise22]

Really need some advice as I am so conflicted about what to do. Apologies this may be a long post.

DS is 9 months old and has always been a terrible sleeper. From about 4 months old he has been in his cot for the first couple of hours, usually needing me to go to him evert 45 mins then our bed for the rest of the night. He would only feed to sleep or sleep in the car/pushchair for naps.

A couple of weeks ago we had a sleep consultant write us a plan. This involved sleep training by going in and out of his room - out for 30secs whilst he's crying and back in for 1m30 to pat him in his cot. Up until about 15mins. If he was still crying at this point pick him up and pace with him until he falls asleep.

It worked amazingly, I couldn't believe it. Within a couple of days he was sleeping 30mins in the morning, 2 hours in the afternoon and 7pm - 6am (with two dream feeds during the night) and settling himself without crying.

Until two days ago and now it's gone completely to put. He's bawling every time he goes into his cot and keeps crying even when I get to the point of pacing with him. Last night he woke up screaming every 45mins until I couldn't hack it and brought him to bed with me.

Nap this morning had been the same and I don't know what to do now. Do we soldier on? Give up? Resort to CC? (I'm not keen but DP is).

I don't think there's anything else bothering him, he's not poorly, I've tried giving paracetamol before putting him down. He seems fine in himself during the day. But now I'm worried I'm causing him harm through all this crying, it seems so distressing for him but I don't understand why it worked so well for 10 days!

It sounds like so called "extinction burst":

www.preciouslittlesleep.com/extinction-burst/
drgeraldstein.wordpress.com/2010/03/11/what-children-need-from-parents-iii-beware-the-extinction-burst/

It may happen in many instances outside of sleep training (e.g. my DD went through something similar with tooth brushing and nappy changes - and there were lots of tears and screams).

I think only you and your DP can decide on what to do next (persist or give up). I know I would have persisted but other families would make very different choices.

Thanks for your reply @wintertravel1980 that was an interesting read. After a slightly better evening tonight I am feeling a bit more confident so think we will try and persist a little longer. If we can get things back to how they were last week it will be in the best interest of the whole family having got this far.

I never did sleep training with either of my boys, so I cannot offer any experience with that.

What I will say though is even with two babies that naturally very quickly fell into a pattern of sleeping through, I still had a lot of random, unsettled nights with both. With teething, feeling unwell, losing the dummy etc. There was always times when they would be a nightmare at night time and then randomly settle back down again after a few nights or so. Although on the whole they 'slept through' it wasn't really until they were a year old that I stopped getting disturbed at night.

Persist. I think sometimes something unsettles them for a few days.

Thanks @Fatted and @CherryPavlova I'm trying really hard to keep going. I'm just so exhausted, I was already knackered from the first 10days of getting up for dream feeds and now it's just worse again it's really hard to stay strong. He's now been up for an hour with me going in and out and pacing the room with him.

I'm really worried that he's just learning that if he cries for 15mins I'll eventually pick him up. The sleep consultant insists this rarely happens, but isn't that exactly what I'm teaching him by doing it every time?