5.5 month DS suddenly up all night screaming

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About a week ago my gorgeous DS had a sickness and diahorrea bug which resulted in him hardly drinking or eating for a few days (which I know is normal) since then he has started to eat back to his usual self but for the past few nights he is now up for the majority of the night screaming
I have given him a bottle a couple of times thinking he was catching up on food missed during unwell and although he drinks it he doesn't seem to want it
He goes off to sleep as normal bottle and bed and mostly in bed by 7pm by from anywhere between 11and 12 he is up proper screaming- once I pick him up within a minute he is asleep in my arms but when I try to put him in his cot he is awake and crying and screaming some more - it ended up last night where I was laid on the floor next to him whilst he fell asleep
Is this a normal regression at this age as up til this last week he slept straight through from 7pm -6am
Help!!!!!

My DD did not sleep well between 4-8 months. Combination of the 4 month regression and teething as far as I could work out. Her first ones didn't come through until about 7 months.

They are 'supposed' to have a sleep regression at 4 months but it is also the time when first teeth come through which can give them problems. Could also be a passing clingy phase?

I'm in pretty much the same boat as you, just getting over a virus and sleep in horrendous. Two little teeth have just come through on the bottom so I'm guessing that's a very strong factor.

We are cosleeping through it at the moment, which isn't ideal as I don't sleep very well, but it is better than dealing with the screaming. Unfortunately DS is on medication that means he can't have teething gels but teething powders do seem to calm him and are homeopathic so I'm happily giving them before bed each night and when we wakes during the night.

However he's also waking up WIDE AWAKE and chatting at 4am! Not crying until I try to get him back to sleep so doesn't seem in pain. I'm at a loss!