This is a cross post, so forgive me...
On Friday morning DS got his 4 month vaccines. Starting that afternoon until Sunday morning he was running a fever and miserable. He perked up a little Sunday morning and while still a bit out of his normal, calm element, he seemed fine. That night he didn't want to sleep in his crib so I had him by me in our bed (we bed share every once in a while- flame away). The next morning he had a runny nose and was super cranky. When I tried to feed him his bottle (I EP) he fussed the ENTIRE time before, during and after. Yesterday morning and today he woke up at 4:30a, screaming and crying. I'd get his bottle and have DH feed him while I pumped but he'd keep crying. In addition, this morning he has a distinct cough. Throughout the past few days it seems whenever he is down for a while (like usual when I'm cooking dinner or whatnot) he gets super fussy. He's also a lot crankier than usual in general. Could these be a combination of things? Could he just have a cold and doesn't eat like usual because of it? He's been STTN since week 8 and is normally a very calm/happy baby. Any ideas? DH and I are getting really exhausted and frustrated that we don't know what to do. Not frustrated with LO of course since he can't control it and can't express what's wrong, but we just feel helpless and want to make him feel better.
Re: Vaccine issues? Cold? Wonder Week?
It could just be a cold and he's fussy during meals because of sinus pressure and a stuffy nose, but since he just got his vaccines, I'd want to rule out a reaction, especially since he'll be getting more of the same injections in the future.
Sounds like you're doing a great job helping him through this. 4 months is also a common time for babies to be distractable during feedings and for teeth to come in, which can also cause fever and runny nose. This is good practice for nurturing him through these challenging milestones. Good luck!
This is what came to mind reading your description, OP. Be prepared for everything (but especially sleep) to change, but not necessarily go back to what you had before. As will happen again, repeatedly, in the future.