Is this gyno or male breast cancer

So for the past month the lyphnodes under my arm have hurt, no obvious signs of infection and sometimes get pain in my groin area but unsure if this is from sitting to much as I work at a desk. No palpable masses in my armpits or groin but I feel a firm but slightly squishy mass under my left nippple that is not on the right. The ER docs said ot was nothing and say my blood work was fine. I have been slightly overweight for most of my life amd I remember when I was younger having issues with my nipples. They'd be sore and sometimes seem to almost lactate. None of that as a adult and I paid no attention to them until my armpit lyphnodes started hurting. I definitely feel something in there, kinda squishy and does move a little bit when pressed around. Definitely not rock hard as I've heard cancer tumors described. Im also 28 years old. Im getting a mammogram and everything done ASAP just curious other people's takes. One other thing i noticed is the area above my nipple, so upper breast area is noticebly firmer on the affected side than the other.