Is this the 4 month sleep regression?

[RR24]

Hello. I am a FTM to a 15 week baby boy.
He has a cows milk protein allergy, and it took sometime to get his formula right. Just when we felt we had his unsettled period (due to allergy) under control, his day time napping has become an issue. About 2-3 weeks ago, his naps suddenly started to only last 20-30 mins at a time. His fussiness is constant. He needs A LOT of soothing and settling to get to sleep. Is this the 4 month sleep regression?
The only reason I doubt it is that his night sleep has not been affected. He sleeps the night and has done since about 8 weeks. Since this phase has started, he does not wake at night. Could it be possible that his formula is still not right?
Any advice is much appreciated

Hi
My LO is 9 months now but our 4 month regression definitely affected naps first then all sleep went awful after a few weeks. Lasted a while for us too. I’d say around 6 months things got a tiny bit easier

My LO has cows milk protein and egg allergy also but breastfed. I would say if it’s an issues with the allergy or food all sleep would be affected and baby would show those other symptoms (tummy discomfort, bowel movements not usual colours and consistency etc)
If it’s only sleep affected I’d say regression over the allergy

Hope it passes for you and baby soon x

Thank you so much, this was huge help.
I was hoping we were in the thick of the regression but maybe not 🙈 after observing for a few days now I'm confident it's not his allergy.