Hi Judy.....I had 23 rads back in August and felt very red and sore quite early. If your skin is broken, the radiologist can give you some special gel/dressing, but if not then loads of aqueous cream, aloe vera 99.9% will help. try not to wear a bra as often as you can and let the air get to it.....a fan or hair dryer on a cool setting is marvellous!! I bought some crop tops from M and S which were fairly supportive but didn't rub anywhere! Good old fashioned colled voiled water and salt helped too.
keep up the skin care for several weeks afterwards as the radiotherapy keeps on working! My breast is still quite swollen and tender at times, and my first year mammo showed up the skin thickening and tissue damage....Which was very interesting to see.
even though you feel tired, try some gentle exercise every day which does help.....I have found that the tiredness continues for several months, at times still feel that I could do with a nap, but maybe that's old age creeping up!!!
take care xo