Alopecia X in a Pomeranian

Hi everyone, my dog has been suffering from alopecia for quite a while now. He has lost almost all the fur on his back. I’ve tried the implant, dietary supplements, and another tablet whose name I can't remember, but nothing seems to work; his fur just won't grow back. I'm at my wits' end and don't know what to do anymore. If anyone has any ideas or suggestions, I’d really appreciate it.

Thanks in advance