Does my father need dialysis?

My dad was suddenly dignosed with CKD in Jan 2018 - everything was ok in Dec 2017. From Jan to Aug 2018, his creatinine steadily dropped with the help of a controlled diet and was 2.9 when he started accumulating fluid in his chest cavity. He was advised to go for a CABG which he did after which he needed dialysis as his urine output was NIL. After about 12 sessions he was off dialysis for about 2 months. In Nov 2018, after a trip to a hill station, he started retaining fluid again, urine was clear (no impurities were getting filtered) and creatinine started climbing steadily and reached 7.0. He was asked to start dialysis again and has been on it for 2 months. His creatinine levels are 3.2 now and urine output above average. Water intake is low and over the past week, he's been having episodes that involve profuse sweating, nausea, black outs (that he doesn't have any recollection of) and vomitting. Could he possibly be getting dehydrated?