Hi, thanks for your query. You seem to have a boil over the area. Sweat and moisture facilitate the growth of bacteria and fungus making this area prone to infection. Pain and tenderness indicate collection of pus. Hot fomentation will help. Hydrocortisone cream is not required, instead apply an antibiotic cream. You need to take oral antibiotics and pain killers.Pus may be drained by a simple non invasive procedure called incision and drainage. You may consult a doctor for this. Maintain good hygiene and wear loose fitting clothes. Hope this helps you.