Swollen, painful breasts with hard lump...?

My breasts have been extremely sore the past few days. Thought I was pregnant, but I took a test and it was negative. So then I thought it was ovulation pain or maybe I ovulated late, but that's not the case either. Well just this morning, I woke up and they were VERY swollen, feeling super heavy and sore and I felt a very thick, solid lump in my left breast. I was almost crying in pain. This has never happened before.

When I touch it the pain is immense. The lump is very big I scared myself into thinking it's breast cancer but I read that it's usually cancer if the lump ISN'T painful? I'm so nervous. What could this be...? I'm going to have a breast exam done soon, but I just need some advice to calm my nerves. 😔