My dx is Mixed Connective Tissue Disease - Lupus, Sjogren's, RA and psoriasis. My rheumy found the sore patches that I've had in my scalp since I was a teenager and called that psoriasis. She also thinks that this could be the cause of the strange, flaky sores that I would get. She also mentioned that some of my joint pain could come from psoriatic arthritis.
I haven't had a scalp sore or one of those sores on my skin since she started me on Plaquenil!