Had breast cancer now terrified about kidney problems.

Hi, Last year I had breast cancer which was treated with a Lumpectomy, Radiotherapy & Tamoxifen which I found very traumatising because I have very severe health anxiety.  About a month ago, I started getting severe upper back pains which went all down my shoulders arms and even my fingers.  I panicked that my breast cancer had returned but I saw a GP, Physio and my BCN who all assure me it’s not related but I took some convincing.  I’m very obese and my BCN did tell me to walk every day and reduce food portions.  I try but I struggle to walk far at all.  The back pain was starting to ease but last Wednesday, because I’m on Ramipril for high blood pressure, I had to have a routine blood test which came back with high cholesterol 7.4 and something called creatinine was also high and this can apparently mean kidney disease.  The GP briefly rang to say he’s not alarmed because my kidney function is 57% but for years it’s been 60 something so it’s nothing major.  However, I googled it and now I am terrified it’s kidney cancer or failure.  I didn’t get to say I’ve been peeing very frequently lately but when I go there’s not much liquid and also my back pain is back but it’s in my lower back now on one side. I was sure I had a urine infection but I had a urine sample test which was negative.   My husband is adamant it’s all down to anxiety and he gets angry and frustrated with me crying and stressing all the time which makes me feel worse.  I’m due to have 18 weeks of therapy for my health anxiety but apparently there’s a 2 month wait.  I feel like I’m going to have a nervous breakdown.  Please help. I’m very grateful for any advice, prayers or support.  Thanks.