Hi- I have Lupus, which is in the same family of diseases as Fibromyalgia. I was exhausted when I was at my lowest point, which is usually when people are diagnosed. Sometimes symptoms come on gradually, which is why many people take years to get an accurate diagnosis. Also, many of the diseases in that group have flares, or increased disease activity, and then "remission" or times when the symptoms seem to be more manageable. I know for me personally, it took a year or so of incrementally increasing doses of medication to find what was the best combination, plus the wait time to see if each increase was beneficial. Some medications take 4 weeks or longer to see the full benefits.
The biggest key to this family of diseases is learning your limits and being ok with taking a break, something we moms have a difficult time doing. For instance, my friends think I'm spoiled because I have a lady that comes to help clean the house every other week. We chose to do that instead of sacrificing time with our children. They're only young once and I don't want to be exhausted in bed all the time.
I don't know anyone with Fibromyalgia, but 10 medications does seem like an awful lot. When you add that many meds at one time, it's difficult to differentiate what is helping.
Good luck to your sister and just be there for her. It's so difficult when you feel like your body is betraying you by being sick.
J.