A few weeks ago I cut my labia majora while shaving, pretty badly, and now it has a small lump there. It's not itchy, painful or irritating at all. It doesn't look like a pimple or a wart and it doesn't have any dis-colouring and I was just wondering what it is? And should I be worried?

It's called scar tissue. As long as there is no pain, swelling or heat around the area, it should be fine.