Rash and bumps on boobs?

I read this could possibly be breast cancer and resembles the photos I researched. I did go to the beach a couple times this week and thought It could possibly be from sweat or allergies. Has anybody had something like this before? (Also I’ve had a persistent stabbing pain in my throat that doesn’t feel like an illness. And the emergency room couldn’t figure it out- Lymph notes being swollen are a sign of breast cancer too)