Definitely take her to the GP and get her checked out, in case there is an underlying infection. Also suss out the possibility of reflux to rule that out.

I took my DD to sleep centre around this age, similar issue except in our case she would sleep from 35-55 mins then wake. My sleep deprivation was so severe after a couple of months that I was hallucinating during the day. Several things: her weight gain had plateau'd, so they recommended I feed her differently. Not more food, but more energy dense foods. Eg add a bit of grated cheese or butter or full cream milk to the food I was preparing and a bit more protein. Also, they had me start offering the 3rd boob, eg when they are feeding well during the day and have had both boobs, you can either offer them the 1st boob again or let them play for a little while and then offer the 1st boob again. Letting them have a good long comfort suck at those feeds in the day when you have the time and space for it can help with this as well.

They also got me to give her a dream feed (except it was never really a dream feed, she would wake) around 10-11pm, then no more boobie until after 5-6 am. This helped break the wake-boobie association, while still providing sufficient "overnight" feeds to meet her nutritional needs.

I believe these 2 measures helped enormously. My DD's pattern was really badly entrenched, it had been going on for the better part of 5 months. I had exhausted ever other method several times over so we did some controlled comforting - not a CIO method, but not an attachment method either. At the same time I experimented with music and lighting (darker or lighter, nightlights, etc) until I got the right amount of light for me to resettle her without it disturbing her. I don't think any one thing fixed it, it was the combination of everything working together. I know the sleep centres are not for everyone, but it did provide me with a supportive environment to make the changes that were needed to turn a corner. Hopefully you will be able to resolve this with some simple measures, but if you can't, don't be afraid to seek out some assistance.