Breast lump

I had sharpe pains in my left arm last night,as I lifted it I noticed on my left breast I had a lump behind the nipple,now I have full ache in arm and breast,I've seen GP this morning and she has referred me for a mammogram and I have a wait within two weeks,has anyone else been like this as I'm wondering if it's my hormones as I'm 48 and perimenopausal?