I Have A Hard Small Lump On My Shoulder. It

I have a hard small lump on my shoulder. It is located on the tip of my left acromion (I googled this to try and be more specific). It hurts when I touch it, the pain is almost the same as when touching a bruise. Skin looks the same. The lump is slighly smaller than a pinky nail, hard and doesn't move. It is not completely spherical, kind of like a "()" shape. Asked my dad who is a doctor, he said it was a calcification but he didn't run any tests and once I almost died from apendicitis because he told me it was nothing.
How do I make a doctor run a biopsy? I have a healthplan but I don't know what to do exactly.