Fussy baby - non-stop crying, day only

My LO has just turned 4 weeks and in the last 2/3 days we’ve noticed that he literally won’t stop crying during the day. I can tell he is overtired and needs a nap but he just is so not ready to settle - we go hours with him sleeping for a max of 10-15 mins before he wakes up screaming (at first I thought it was cause I was putting him down but now even with contact naps, it’s the same) and then it takes so long to try and settle him and at times he won’t settle and just screams for hours. Seems to happen from about 7am to about 4/5pm - he then eventually settles at 5pm and is able to sleep through until he’s hungry (every 1.5/ 2 hours for a feed) and then quickly falls back asleep. I don’t think it’s colic as otherwise this would be something that happened all day? He passes wind a lot and doesn’t have problems doing so and poops large poops every 1-2 days. I’m on my own during the day and honestly I’m losing the will to live and feeling the worst mum in the world because I just cannot work out what’s wrong. Help, from a desperate mum.