Hello and thanks for your post,

We can't diagnose anyone on the forum, or offer medical advice. There are many different reasons why lumps appear and most of them won't be as serious as cancer particularly as you have had this lump for such a long time. Most lumps have straightforward explanations.

I would make an appointment with your GP, so you can hopefully put your mind at rest. 

Try not to overthink it all but do get it checked out.

All the best,

Catherine