Breast, armpit and arm pain/discomfort

I’m going out of my mind with this. I’ve had it for around 13/14 weeks now, started with a quick shooting pain in my right breast/nipple which is now a dull ache with the occasional jab, and it seems to have made its way up to my armpit (clothes feel much tighter on my right arm and it feels like a sting under my armpit sometimes) and then I get a shooting pain down my arm and it feels a bit heavy.

I’ve been to my GP who put me on antibiotics as he thought it could have been mastitis (I’m not BF) also examed my breast, the antibiotics didn’t help so I went back and he referred me to the symptomatic breast clinic and I’m waiting on my appointment (it’s been about 3 weeks).

I’m a little bit worried in case it’s something more sinister and I’ve been waiting this long to be seen.

Has anybody been through this?