I understand he's old and that these things happen to cats as they age but I want to figure out what's up. He gets constipated from time to time so I started giving him a dash of miralax in his food (less than a pinch) every other day to keep his bowels regular (this was at the recommendation of an [expensive] vet. He's been getting that regimen for about 6 weeks now. We also switched his good to weruva grain free with the occasional classic grain-free fancy feast as a treat. He has a lot of energy (too much) and meows an awful lot at night when he wants food at the wee hours of the morning. He also loves knocking over knick knacks before settling into bed.
As I said, the bald patch appeared 3 weeks ago. It started as a small light pink bald dot that looked like a scab maybe the size of a tic tac. Since then the skin on the patch has turned white--it no longer looks like a scab and has small black dots in the lower region of the patch which has now grown to the size of dime. I've attached some pictures of the patch.
Does anyone know what this could be? He has not increased scratching himself at all and he is not an outdoors cat. We have no other pets in our household but our apartment could use a cleaning...sigh.
Any help or advice would be great. Thank you!!