Thrush? *TMI*

Since having a baby 9 months ago I now get thrush a few days before every period. I assumed it may be a pH imbalance that would settle down with my hormones but it’s starting to get me down now. I’m due on in a few days and yesterday I got super itchy to the point of being painful down below and the whole of the outside of my vagina was very sore, red, and swollen. I showered and slept without underwear and this morning I felt a little better but I’m a bit worried. I had a smear test about 7 months ago so I know I’m definitely clear of STIs etc, but with that being ruled out I’m not sure what else it may be. I can’t do this every month 🙁

Any suggestions? Anyone experienced this?