9 month old good sleeper now terrible!

[GipsyDanger]

As it says. My 9 month old ds was a great sleeper as a new born. Over the last month or so he's had 6 teeth come in, a bad cold.
He usually would have his last bottle at 7ish (sometime earlier) that would knock him out and he'd sleep till 6am.
Now however he's wide awake most nights after his bottle. He's waking up crying multiple times. It's taking us about 2 hours to get him to settle (so 9pm at this point) and he's waking at 11pm 2/3 or 3/4 with mini wakings where you just put his dummy back in and he sleeps.

To get any sleep, either dh or I will sleep beside him on a mattress on the floor in his room when he wakes at 3/4am and he'll then sleep to 6/7am.

Any advice on how to get him to sleep through or where we're going wrong would be great.

How does he go to sleep at bedtime? Ideally he needs to be falling to sleep in his cot.

Why can't he put h8s own dummy back in? Can he find his dumny easily at night? Assuming he can, practice picking the dummy (the wrong way around) up off the floor and puttibg it in himself.

I'm going through the same. Dd was always a great sleeper slept through from 3 months old. Usually a bottle at 7 and asleep by half 7 then up at 7. Now she's awake till 9/9.30 and keeps waking in the night. Last night she woke up at least 9 times crying and crying, pretty sure she's teething but because she never really crys it's worrying