I'm 29, but I've been experiencing these "flare-ups" since I was 19, about two years after my IBS started. My symptoms have included extreme fatigue, severe muscle and joint pain, joint swelling, sun sensitivity and skin rashes (which I always thought was just sensitive skin or acne that I only had during the summer). I've had other symptoms over the years, but they were so mild that I never really bothered with them (some mouth ulcers, a bit of hair loss) and never thought that they were connected. Now I see that they're probably all part of lupus.
The last two years have been really bad, which I don't like to talk about, especially with the severity of fatigue and pain. Anyway, a lot of these symptoms finally had been showing up at the same time, so I think it was easier for my PCP to refer me to a rheumatologist. I really thought I had RA or fibro when I realized I couldn't explain the constant pain and fatigue on IBS (especially once I got stable). I've learned that a lot of people with lupus also have GI problems and lactose intolerance! But it's not something that's used to diagnose lupus with - just overlapping syndromes.
I've just been reading up on lupus and wondering what the future will bring!