So I think I've had it longer but I only noticed it in April this year as I I'm a side sleeper and for once decided to sleep on my opposite side as my hip was hurting and I found the following 

1cm or a little larger vertical mass/ridge on the outer edge of my right breast not the edge closer to my breast bone. It sits just under the outer edge of my breast tissue at round about the fourth / fifth rib I think as it kinda aligns with the central line of my breast. 

There are no other warning signs. No dimpling, redness or tethering. The mass) ridge seems to sit against my rib and changes shape slightly depending on the position of my arm or body. For example if I bend forward it's less pronounced and more compact if I stretch on my side with my arm up it's more visible but more spread out?

It does not seem to move with my breast tissue. If I bend forward it stays against my rib if I lay on my left side my tissue drops left that stays put. It does have some movement. If I put a finger on either side of it I can make it slip/jump side to side between the two fingers along my rib. 

The outer edge feels like a drop off towards my outer rib where the inner edge in my breast feels like it's blending more with my chest wall. So it's not a lump in a traditional sense in my mind though I can palpitate around it if I poke hard enough. It's firmer but does have squishier areas over and around it. Which I think I've made worse my constant pressing and poking literally every day.

I'm not sure if relevant but I constantly sleep on that side. I have terrible posture and spend the last six years at a computer desk I had set up off to my left side so my body was mostly twisted to the left for alot of hours sat down during though years. I have pain in multiple ribs in a band on my right from the front to my back and behind my shoulder blade on that side too.

I also in the last year got an Akita puppy who loves to flying tackle you. He us about 45kg and I bruise easy he has the amazing ability to smack me in that side of my chest and back and has hurt and kicked my in that breast multiple times at least with his full weight. 

Now I'm scared as I had a scare teo years back with a small lump in sane breast that after ultrasound, mammogram and biopsy was duct ectasia but that seems to be permanent as the lump never went away and the area around that is thicker like scarring.i dud have that rechecked by my go this year and they were not concerned with that at all still being there.

I dunno if this mass is something to be scared about or if I've caused that much trauma to a muscle or tendon or something in that side of my chest that I've caused a permanent ridge/lump. 

It doesn't seem to react like I would expect a breast lump to react. Hasent changed size from April with the exception of my poking causing localised swelling. 

I'm scared and waiting for the inflammation to go down a little and gain courage to book in with a doctor but I feel because I got lucky once my luck has now run out and this is the end for me :( 

I'm 42 female and going through perimenopause and my health anxiety is through the roof. In the last year I've convinced myself I'm dying of one form of cancer or another. 

Standard risk

my mom and sister were prone to none cancerous breast lumps