Hi, I've Had A Lump On My Forehead For Two

Hi, I've had a lump on my forehead for two months now. I don't know if it's been there longer but I only noticed it then. I was washing my hair and could feel it burning. It feels like a burning pain almost daily, even if I'm lying down on my stomach or if I accidentally touch it. I've been having headaches every day and they go away when I go to sleep but start again in the morning. I'm very worried but can't get a doctors appointment til the 24th January. The lump isn't visible and everyone seems to think it's a pimple under the skin but surely this wouldn't cause so much pain?