Almost pure blood and blood clots in urine

Going through another episode of urinating almost pure blood (fresh looking) and passed a large blood clot yesterday. Have had CT scan and ultrasound and cystoscopy but nothing found so far. Also pain in left side/back that might be kidney pain. Anyone go through this? I have a call in to urologist and should hear back today. Also I had asked my NP for antibiotic, Cipro, which I took but on day 5 fresh blood showed up in urine again and I stopped. Asked for it in case of infection that might not be showing up. The last time I had gross hematuria and clots (and vomiting) the urologist's nurse saw me on emergency visit and prescribed nitrofur mac which appeared to clear it up, but started up again several weeks later. So frustrated and worried!