I get bumps down there too sometimes. If they go away, don't itch and don't hurt, don't blister open or do anything like that, then I wouldn't worry. I get lumps in my earlobes too sometimes. One or two usually, and they'll appear overnight, hang around for a few weeks, and slowly fade away.
I believe that some conditions like this are caused by nerve cells, but mine certainly feel more like hard or liquid filled lumps. They're not painful either, and they go away, so I don't worry about them. I had one in my neck too, for years. It's finally gone.