Localized pains

Hannah • Jesus-Loving Teenager😘
Hi ladies- I never normally post things but am hoping for some advice, please?:/ 
 I've had pain in my left breast for over a month now (see attached image where marked days are days where it was particularly painful) and recently I've noticed a small internal lump forming on the underneath of it. A lot of the time the pain is partnered with a really severe headache going straight through my eyes and into the back of my head. I've tried talking to people and using the Internet but everyone just seems desperate to tell me it's cancerous/the worst case scenario so am hoping someone could maybe give me some solid advice? I very rarely go to my GP so I'm not sure if this is GP-worthy? Thanks in advance. 🙃