What Causes Increase In Creatinine Level After Taking BP Medication?

Question: My dad has diabetes. His blood pressure spiked a couple of weeks ago, and he ended up in the ER. They told him he needs to see a nephrologist and check out his kidneys. The nephrologist ordered an ultrasound, which showed that one of the kidneys was fine, but they couldn't see the other one well. Instead of ordering a repeat ultrasound, the nephrologist ordered an MRI of the kidneys. The MRI is scheduled for later today. In the meantime, my dad's creatinine levels have gone up from 1.4 as of two weeks ago, to 2.07 as of yesterday. We believe that the creatinine levels have gone up as a response to the blood pressure medication my dad has been given. The blood pressure medication works well to control the blood pressure, but my dad is afraid to take it because of the negative effect on creatinine. When he doesn't take the medicine, the blood pressure goes up. My dad is terrified that he'll end up having to go on dialysis -- his mom was on dialysis for years before she died.The nephrologist is unresponsive -- she accepts communication only by e-mail, and then doesn't reply for days. What should he do while he awaits the MRI results and the nephrologist appointment in a couple of weeks -- continue to take the blood pressure medication and risk the creatinine levels going even higher, or stop taking the meds and risk having the blood pressure spike? Any advice would be very much appreciated! Thank you for your help!