Need help please my 5 month old is giving me anxiety when it comes to bedtime

[Fallingwhere]

So, I moved my baby in his room at 4.5 months so he can get used to his room and I sleep on the floor and planning to untill he is 7/8 months. He was a great sleeper, he slept for 4/5 hours stretch and woke up fussing for change or feed twice a night.
For the past 2 weeks, he is fine with his day naps he sleeps on me most of the time and he is good with his usual bedtime routine at 7/8pm but as soon as the light is turned off he is screaming his head off, crying, arching his back and hitting me. This goes on for 20min untill he falls asleep. I put him in bed then throughout the night he wakes up screaming and crying every hour. I try to pat him and sing but that makes him scream cry even more. I eventually pick him up and again after 20 mins he falls asleep and the cycle continues untill the morning.

He started rejecting his dummy at night when this tantrum started and nothing I do calms him down including holding him. We are both so tired and don't know what to do. I wake up with headache because of him screaming in my ear all night and super tired. I feel guilty that I don't have energy to play with him as much, take him out, cook or clean the house. I am running out of patience and feel bad when I get annoyed at him too. Night time is just filled with anxiety now with anticipation of him screaming ours and our neighbours house down.

He has started crying when traveling at night too where he was fine before. We bought him a little bunny light from IKEA. He stares at it and eventually falls asleep.

Is it sleep regression? Teething? Scared of dark? Is he ill?

Why on earth are you sleeping in the floor in his room? No wonder you are finding it so hard! Take him back to your room, if he wakes in the night, pop him into your bed and cosleep(following the guidelines) It sounds like it could be a fussy phase, babies do that, their sleep goes up and down for a variety of reasons.

Your baby is napping on you during the day and suddenly at night is left on his own in the dark.

you need to be consistent. Do the day naps also in the cot. Do exactly the same settling techniques for day and night.

Sorry, to clarify mattress on the floor. I am not sleeping on hard floor lol that would be very painful.

Shall I make the room dark at day time too or just cot and white noise?

I think you've got yourself in a right fankle. Why not move him to his own room when he's 8 months and have him in his cot/next-to-me in your room until then? Sleeping on a mattress on the floor sounds miserable.

I'd embrace the contact naps for now if you enjoy them and make a decision on when he's moving to his own room, at which point he should be napping there too.

Persevere with the dummy. Cuddle him tight and bounce/rock him while putting the dummy in and ssshhing. He'll give in to the comfort and motion eventually. It'll pay off when he's older and you can place lots of dummies in the cot for him to find and self-soothe in the night.

And yes, naps should be exactly like night time sleep. So for us that's pitch black, lullaby music on quietly, sleeping bag on over day clothes, dummies and favourite teddy. All the usual sleep cues.