Oh Anna - we've had times like this too.. especially around that 3 month mark! It's very normal for them to go through this stage. Ours was compounded by AF making a return, giving us some fussiness on the breast, so we definitely had some unsettled times where I could only get him to sleep, and stay asleep on me. It's probably something you'll just have to wait out, and it'll soon pass.

Once you rule out pain, nappy, hunger etc... it's so hard to know what to do. You're doing a great job comforting Jett tho. Hopefully he'll settle down for you again soon.