How can I fix my pom’s skin?

I have a 12 year old black Pomeranian. Holly, has always had skin issues it seems. Dry, itchy, sores and so on. I read on another site how its my fault because I’ve always had her shaved into a lion cut. The vets have never said this was harmful. Now I see it probably hasn’t been too great of a choice. She also has a lot of dandruff. I read how this is also my fault for using the wrong shampoo. If it is, I take full responsibility. She’s my best friend though. Is it too late to fix it? Can I still fix her skin with hair growth formula and proper shampoo?