Feline Fur Loss

Bucky, one of my semi-feral cats has been having a bout of fur loss over the past couple of months. There is no itching or redness. (I've seen it on a couple more of the cats I care for outside, but not to this extent, and there's no indication it's been spreading since some of the other cats don't have it.)
Bucky has had it before and previously switching foods to ones without grains and taking Animals' Apawthecary Detox Blend has solved the problem, but he's been rejecting that.
It started around the ears and moved down to his shoulders. Now I'm seeing patches gone on his legs. The rest of him has beautiful, thick black fur.
He commonly has something else going on (sneezing or runny eyes), so I've been using homeopathy when needed and supplementing him for his immune system for years. It probably would be next to impossible to catch him to take him to the vet in case it's hypothyroidism (which is very rare in cats), but he's not always around to give him his medicine. Additionally, when he really isn't feeling well, he hangs around the patio and sleeps all the time. He hasn't been doing that and has a good appetite.
Just in case it was bacterial, I started giving him some amoxicillan a few days ago. (It's Fish Mox, which can be given off-label to cats.)
Bucky has slowed down with this, but other than that, he's not giving me any indication he's suffering. He's at least 7 years old, so he's middle-aged at least, and it could be from that, too. He does have some gray hairs in his fur, but none around the muzzle, so I doubt he's a senior.
Thank you.