My mom had open heart surgery on the 8th.  She has developed a rash under her breasts and on the front of her sides if that makes sense.  They are red welps and itchy.  What could this be.  She has been on same medication since she left hospital so I dont think is medicine related.
Itchy patches need to be taken into account. If your mother is diabetic, rule out fungal infection. Under skin of breast is at times not cleaned properly, so it can lead to skin infection. Take opinion of skin specialist.