This is where experience comes into play.
Gather 'round kiddies, let The Rain tell you a story. Loooong ago (a few months) Mr Rain found a largish lump right under the dodad as well.
It took a lot of corrage for me to tell people, but fear of cancer was too great not to. I went to the doctor who felt me up, and had to go get it ultrasound with a doppler thingy (no idea how it works), and came out later it was a cluster of veins. Don't go, 'oh phew, it most likely be the same for me,' CHECK IT OUT NOW! All I learnt from my stroy is the fact that the embarrisment of showing off your junk to people you really don't want to only stems from yourself. They've done it a million times and are so old of it.
I felt bad for now on hindsight for keeping myself so long to do it. Go do it man. Don't let fear get to ya. Tell your parents or go yourself. Everyone understands and are really relaxed about it. Your mum or dad won't say a word and the doctors don't give a damn.