How can I manage severe chemo side effects?

Hi everyone, My name is Joanne and I just joined. I was diagnosed with DCIS estrogen negative in 2023. I had a lumpectomy and did radiation. I continued to have mammograms every 6 months, and all was good until last October when they spotted what they believed was probably fat necrosis from the surgery, so they labeled it "probably benign". I had another mammogram mid April of this year and another ultrasound and again "probably benign ". I felt a good size lump in the same exact area they'd been watching on Mother's Day and it turns out it is a tumor. I really wish a biopsy was done last October but I was told they don't biopsy every suspicious spot. I say bs, I had cancer in this breast less than 2 years prior you should definitely do a biopsy. Anyway, I started chemo on July 16th and I had a horrible 9 or so days, with, pain from the shot they give the day after that heightens your white blood cells, constipation which then lead to diarrhea for almost a week straight, dehydration and I also had a mouth sore and thrush. Oh and a sinus infection! I have my next chemo scheduled for August 10th and I am so afraid to go through it all over again. After 6 treatments of chemo which are every three weeks I have to have a mastectomy then 6 more months of chemo. Thank you for letting me share this. If anyone has had any similar reactions to chemo and can offer any possible help with side effects it would be greatly appreciated. ❤️