I understand your feeling and your condition too.
There is no need to worry about this because this is a common condition that every women face. There are two possibilities and those might be due to excessive heat your skin is of dry type and it is getting cracked and shedding another might be because of heat you might be sweating excessively and there is chance of fungal infection and because of that your asking is dry and there is itching. For that you can do thing s like water. 2-3 liters a day and avoid the excess sweat on your breast so that you won't face it once again.