Red spot on nipple, sign of IBC? /Breast cancer? I'm 26 with likely PCOS but undiagnosed

[Nonoanddefintelyno]

A family member got diagnosed with lung cancer six months ago so it's making me extra paranoid about my body

Then you make an appointment with your gp ASAP and see what they say. Nobody here can possibly say, OP. Only the GP can help you on to the referral pathway.

Hard to say, but typically IBC (I think) is more like a red patch on the breast itself as though you'd been slapped but no associated pain or lump rather than a discrete spot? But if it's new it's worth getting checked.

On the nipple or the areola? If areola it's most likely an inflamed Montgomeries turbicle. But you need to see a GP to be sure.