Brief Answer:
It is a yeast infection
Detailed Answer:
Dear young lady,
From what you describe, it seems to be a yeast infection spread around your vagina, anus and the perineal area. This is treated by 4-6 weeks of local antifungal cream like ketoconazole 5%.
It is very difficult to treat and to have a satisfactory conclusion, that's why it is usually added a systematic antifungal like terbinafine, for which you will need a prescription from your doctor.
I see that you have been previiusly treated for a bacterial infection, and this is another case that needs a specific medication.
I also recommend to keep your perineal area dry, especially after taking a shower or doing sports or other physical activity, since fungal infection grows in humidity.
I hope I have helped you. Wish you good health!
Manoku Eni M.D.