breast lump increased in size

Back in January, I was running up my steps to get ready for work. I was holding my boobs because I wasn't wearing a bra. While running up the steps, I stopped cold. I felt a large lump in my righ breast on the side. I had it examined by my gyno and he said it was nothing to worry about and that it was a fluid filled cyst and that my breasts were probably going through changes as I age. Fast forward to April. I have a cat who doesn't really like me, unless I'm feeding her. Well, since the beginning of April, this cat has been so far up my ass I don't know how I haven't crushed her. She never sleeps with me. But I have noticed she has been favoring my right side. She sleeps on the right side of my head, my right leg, right foot. This past cycle, my boobs were sore, the usual. It usually lets up as soon as I start my period. The soreness. Definitely goes away by the time I finish. But this cycle is different. The lump has progressed to a large almost golf ball sized rock hard lump. I've played with it, it no longer moves. And it creates a burning shooting pain. This pain sometimes radiates down to my armpit and my shoulder has been sore as well. My grandmother had breast cancer. And I am terrified of hearing that. Part of me doesn't want to know. Part of me says that's selfish. I've reached out to a few close friends and only one of them has been keeping me busy and keeping my mind off of this massive lump. The other one couldn't be bothered. She just moved back to town and has a new girlfriend after leaving her wife less than 24 hours ago. I see my doc on Thursday and I hope she sends me for stat testing so we can figure out what is going on inside my breast.