Hello I Have Recently Gained And Lost Weight Which Is

Hello I have recently gained and lost weight which is now causing my breasts to sag and my stomach. I have developed a rash in both areas. it becomes inflamed especially during my menstrual cycle. I have tried topical creams such as lotrimin and anti histamine such as benedryl. That helps a little. Is there anything else I can do myself. its so bad sometimes its very uncomfortable to wear a bra or under garments Thank you