It sounds like a case of Cognitive Dysfunction (brain fog). I have it most days. And it's odd, like you, I also get songs or lines of poetry that seem to play in my mind like a broken record alot. I forget or mix up very simple things like left/right, I get lost in a town that I have lived in for years, and I even forget how to shift the pickup truck I've been driving for twenty plus years now. The best way I can describe it is a lack of mental focus.
Bottom line, brain fog is a very common symptom caused by Lupus. If it concerns you, and is giving you problems, definitely tell your Dr. about it.