I just checked it out, it is red.
i think from what you described i had that many years back. it hurt to walk sometime and whenever i wiped. i was working out alot and my doctor said it was from my sweat. i sweat alot. it was an enlarged cyst. he had to cut it open and drain it. IT HURT!!! He then had me sit in warm water with epson salt every day for about a week if i remember correctly. mine was probably the same size as yours.
From the symptoms it can be due to folliculitis and boil. Folliculitis is the inflammation of one or more hair follicles. The condition may occur anywhere on the skin. Boils are caused by infection of the hair follicle by staph aureus. Please keep the area clean and apply some topical antiseptics. Also wear loose-fitting cotton clothing and use an antibacterial soap or mild soap like dove.Avoid any kind of cosmetics. Topical antibiotics such as mupirocin or neomycin containing ointment are also useful. In case the symptoms persist then oral antibiotics and lancing may be needed. Please consult a dermatologist in that case. Also then pilonidal cyst has to be ruled out.
I sincerely hope that helps. Take care and please do keep me posted on how you are doing.