Is there a link between MS and Psoriasis as they’re both autoimmune diseases. Are there treatments that can help both at the same time?

I was on Tecfidera for 15 years and it kept my Psoriasis and MS under control. When my MS started to decline 4 years ago I was taken off Tecfidera. I have now transitioned to Secondary Progressive MS, and not responding to any of the new treatments. Is there a connection between MS and Psoriasis since they are both autoimmune diseases?