My mother in law has a bump beneath her breast that is swollen red and about the size of her fist . she lifts stuff all day could it be a hernea or?

Unlikely: A mass the size ofa fist is a growth, this needs to be looked at by her doctor. Hernias do not occur in breasts.

Not hernia: While the redness and swelling could indicate an infection, it is critical that she be seen by a general or breast surgeon to make a diagnosis. Given age, one should be concerned that this is an inflammatory breast cancer and have appropriate testing done - if this is a cancer, urgent treatment may be life-saving. Do not wait.