You are having fissure and erythema
in upper part of intergluteal fold. Most probably it is candidal infection superadded with bacterial infection. It is painful condition and you may be having mild itching.
In such condition I usually advise to test blood to rule out DM,HIV and anaemia
You have to improve hygiene by using dettol liquid, take sitz bath in dettol water.
Apply antibiotic cream like mupirocin
, avoid soap bath, take antibiotics, antifungal and anti inflammatory drugs.
Keep the area dry. After healing of fissure, use clotrimazole
powder to cure the the fungal infection
and to prevent the relapse of disease.
I feel, you might improve , but take treatment under supervision of dermatologis.
I hope you got my answer.
Dr. Ilyas Patel MD