Hi,
This could be due to excessive trauma , friction, bacterial infection, fungal infection or dermatitis.
Also, the skin in the regions you mention is normally dark as compared to skin elsewhere.
Do you have any other associated symptoms of itching, rash , etc.
It would not be advisable to scrub the area too hard as this would irritate the skin. You should try to avoid sweat collection in the areas, keep the areas clean, maintain good personal hygiene, wear lose comfortable clothes. Apply calamine lotion at the sites.
Only a clinical examination would be able to give the cause of your symptoms.
Consult a skin specialist for your complaints and discuss whether this is normal or whether a demelanising agent would help in your case. Also discuss with your specialist about microdermabrasion and laser therapy in your case.
Let us know about how you are doing and if you have any other doubts.
Post us about what your doctor advises.
Regards.
Hello,
Without external examination it is very difficult to confirm a diagnosis,but the various possibilities for your symptoms are bruising due to sexual intercourse or overmasturbation,pigmented nevi,lentigo or acanthosis nigricans.
Acanthosis nigricans is a brown to black, poorly defined, velvety hyperpigmentation of the skin, usually present in the posterior and lateral folds of the neck, the axilla, groin, umbilicus, and other areas.
I sincerely advise you to consult a dermatologist and get yourself evaluated for these possibilities.Till then, you should keep the area clean, wear lose comfortable clothes to avoid sweating, use a powder to keep the area dry and use calamine lotion at the sites. Oral antihistamine medications would help if the lesions are itchy.
Hope it helps.Take care and pls do keep me posted if you have any additional doubts