Firstly, go and see your GP and don't worry about getting examined. Not many people realise this but a doctor's perception of the examination is completely different to yours. The GP will be more worried about ruling out diganoses/trying to characterise the lump, he (you should see a male so you feel more comfortable) won't be worried about the aesthetics of your butt.
Secondly, to me it sounds like it could be a pilonidal cyst, especially considering you have a bit of hair there (ingrown hairs cause it.. have you sat in an uncomfortable position for a long period? soldiers used to get it from bumpy jeep rides). It might not be painful now but it could get very painful soon unless you see your GP.
Go to your GP, the examination will literally take one minute and the weight will be lifted off your shoulders, no big deal.