Have you given sardines? I've switched to them instead of giving oils. Meijer carries the Brunswick brand(Canada) and one can per dog every few days has been working, and they love it. I also rotate the coconut oil, but my dogs don't like it as much as sardines.
I use to give 2000mg of fish oil daily, raw fed.
Humidity in your home helps reduce itchy skin.
I try to keep my house at around 25%. Even then I get static shocks now and then.
If you are getting static shocks, you know your air is dry.