Breast health

As a women breast issues can be scary. I just had my second daughter this October and I do breast feed. This summer while I was pregnant I started to get tender on my left breast same side as my armpit. I thought it was due to the tight bra I was wearing. Fast forward, I am still having issues. It’s tender, I don’t feel any lumps that don’t feel like tissue. I am finally getting an ultrasound done to double check and make sure nothing serious is going on. Has anyone else have breast issues before?