Hi, this sounds like the 4 month sleep regression. Hit us hard at 4 months with our baby. So sorry OP and Skyla01, it is a rough time.
I would highly recommend the Little Ones sleep guide: www.littleones.co/
My DH and I did this when we had reached breaking point with the 4 month regression, on recommendation from a mum friend. It is not a ‘quick fix’ and takes time and involves consistent routine, but def helped us a huge amount. So much so we’re planning to use it again for next baby if needed. (You can use it earlier than 4 months but this is when we discovered the method) Really helped to give us the structure and framework we needed to work within to help baby learn to sleep in their own cot and get nap timings right, so they get the right amount during the day (not too much or too little) and this puts them into a better position for sleeping at night. With the guide you can work out your baby’s waking window (where they are rested, alert and happy) and this is the perfect window for going out and doing things but make sure you get back in time for calm settle routine for their next nap, which they will be tired an ready for (avoid over tiredness at all costs, it’s a nightmare! Almost impossible to settle an overtired baby, I always had to resort to breast feeding to sleep if it got to this point, which was a backwards step).
The guide encourages trying to break habit of cat napping which they do so much in the early weeks and ie in buggy, car or on you if breast feeding and get them used to going down in their own bed for naps consistently. I found breaking the dependency of sleeping on mummy a life saver as baby only wanted to sleep on me after feeds and refused to be put down or sleep in her own cot. Although the sleeping on you is lovely at first, it becomes a problem when you can’t put them down for a nap in their own cot/ Moses basket which knocks on to them not settling in their own bed overnight either (plus you’re stuck with a sleeping baby on you and can’t get up/go for a wee/eat/ shower or otherwise have a little break!).
You start out with 3 day naps (short morning, long lunch, short afternoon) and gradually lessen and drop these as baby gets older and needs less day sleep and can stay awake and happy for longer periods. The aim is for them to get used to sleeping in their own bed and learn how to self settle, and be nicely sleepy for bedtime as they have had enough sleep during the day (not too much or little).
Hope that helps 🙂 the sleep guide does cost money but not too much and we found it a real life saver