Has anyone had anything similar? Should I be concerned?
I know you posted this a year ago or so, but to all you people on google who might stumble upon this, i believe what you've described is a Sebacious Cyst. Nothing special, just an area in your upper or possibly deep tissue, that has filled with an infection, white blood cells and protiens. A sort of greasy substance by appearance. Just treat it as a severe pimple, keep your area clean, don't pop it, unless you understand the risk that, yes while temporarily gratifying, it could get infected, and come back or get worse. Either way, give it about 2, maybe 3 weeks, depending on if its getting worse, or just not leaving, then go see your doctor or a dermatologist.
Good Luck everyone!
PS These cysts are most common, on the face, back, scalp, and scrotum, reassuring the fact that i believe its just a sebacious cyst.
j