What drugs are you taking? I know that steroids like prednisone do change the moods.
On a diffferent note, I had something like this happen to me 11 years ago. At first I thought that it was because of the valley we were traveling then I read a book that suggested that it was hormones. The book theorizes that women are taught to be submissive and kind of "take-it-on-the-chin" silently. so at a certain point in there life, they change and decide not to "suffer" in silence. I am not sure if hormones are the case or if it is experiential.
I am not the same person I was in my 20s and 30s. We lost a child 11 years ago. I can guarantee that experience has totally shaped my life and who I am today. I realized that there are things that happen in our lives whether good(ie birth of a child) or bad( death of a loved one, or illness) that shape us. I had to find a new normal for my life, for instance. The new normal has to emcompass what has happened. There was a before and then there is now.
That said, you are not the same. You know a before Lupus came to stay with you and now there is now. Many of go through a mourning time and all or at least some of the stages of grief.
I have promises to keep and miles to go before I sleep, and miles to go before I sleep.......Robert Frost