Breast/Rib/Back Pain

hey guys, so I've had pain in my left breast since August of last year, the pain has seemed to ease since but it's still very bothersome. The pain seems to radiate from my left shoulder blade to my rib and then my breast. I've had tests done (ultra sound, blood test) and been to my doctors a few times, everything has come back negative. I've been examined by doctors, there's no lumps etc... I recently got a full blood test that I will hopefully get the results for this week. I'm going in for another ultrasound soon. The doctors don't know what's causing the pain, they've mentioned that it could be muscle related, they've suggested I go see a someone to help with muscle pain.... but all honesty it doesn't feel muscle related, the pain kind of feels like someones poking me or pushing down really hard on the side of my shoulder blade which makes my whole top left side hurt. It doesn't feel inflamed per se, more like an ache. I'm a little confused as to what it could be? Sometimes my nipples feel itchy/burn and the only unusual thing I've noticed is that the textures in my breasts have changed. Not a dramatic amount but sometimes when I look down on them, they look lop sided and pushed inwards, sort of like how a mango looks, but then when I play around with them, they go back to normal? I was wondering whether anyone has gone through similar pain and symptoms as me? I don't have any relatives with the background of breast cancer and I'm only 19 if that helps.

Thanks in advance! Hope someone can help... It's been too long now and I'm more worried than ever