moist rash on butt cheeks

For a while now i have been getting very sensitive rash  or  little bumps between my cheeks the cheeks get very moist and itch alot , if i put a towl there it will be wet in no time at all , and i dont know why this is  and now there is a lump it feels like a little  ball it comes and goes i noticed , i have also lost my hair back there ,used to be really hairy  this  i noticed came about over the last five years when i started a job that i sit down for ten hours a day ,, it is always very irritated  back there  I havent seen a doctor for it becouse  i am to embarresd too , I would like to know hwat it could be.

[Dr_Aparna]

Hi,
This could be an exzematous lesion.Eczema  is a form of dermatitis, or inflammation of the upper layers of the skin. The term eczema is broadly applied to a range of persistent skin conditions. These include dryness and recurring skin rashes which are characterized by one or more of these symptoms: redness, skin edema (swelling), itching and dryness, crusting, flaking, blistering, cracking, oozing, or bleeding.
Atopic eczema ( atopic dermatitis) is believed to have a hereditary component, and often runs in families whose members also have hay fever and asthma. Itchy rash is particularly noticeable on face and scalp, neck, inside of elbows, behind knees, and buttocks.
Dermatitis is often treated by glucocorticoid (a corticosteroid steroid) ointments, creams or lotions. They do not cure eczema, but are highly effective in controlling or suppressing symptoms in most cases.
ref:http://en.wikipedia.org/wiki/Eczema