Welcome and thanks for posting your query to the forum.
It seems from your problem that you are suffering from the problem of "folliculitis" over the genital area and over armpits.
Folliculitis is a common problem which arises due to blockage of pores of oil glands which are attached to the hair shaft. Due this blockage we feel the sensation of mild itching or tingling
which may get converted into pain sensation.
It is a common problem over hairy areas such as at genital and armpit region. Once the folliculitis is healing it leaves behind the area as blackish crust or scab over the affected area. You need not to do anything for it actively as the scab will fall off by itself in few days of time. At the maximum you can do warm water compresses over the affected area.
For the prevention of this situation in future kinldy follow the suggestions below:
-You should maintain good hygiene
-Wear cotton clothes and cotton undergarments.
-Keep your self away from hot and humid climate.
- Take two times bath.
By maintaining the above things you would be getting rid of the problem. Very specifically to mention is to reduce your weight as is the most important factor in causing the folliculitis problem.
Hope these informations are helpful.
"Wish you good health"
Dr Sanjay Kumar Kanodia
MD (Dermatology & STDs)