Hi Mary - I'm a fellow FM pt. Welcome to Fitday.
MILD, MILD, MILD exercise to begin with then bump it up slowly is what all the books say & from my own experience I agree. I also have to take lots & lots of breaks until that burning muscle feeling abates during the exercises. My doc prescribed a mild pain killer since OTC analgesics weren't strong enough and I take one about 15-30 minutes before my workout. It's not strong enough to affect my head at all and it only takes the edge off the pain. But it's enough that I can get started. I always start with warm ups & lots of stretches.
After I exercise the fatigue & pain is reduced & I move more freely. The fatigue is only increased when the workout was too intense for me/I pushed too hard. The trick is to learn how not to over-do-it, pace yourself, & know when & how hard to push yourself. Every day is different. Good days you can do X amount of something and then on bad days you'll do less. So just accept that and try not to push too hard. I also recommend taking breaks during your routine when the muscle pain flares really bad (I get a serious burning from the lactic acid build up) and by taking breaks you'll end up doing more in the long run plus it helps keep your stamina up. Using Fitday to track it plus use your journal and you'll learn what you can & can't do much, much faster.
Best wishes for a successful journey!
"Most folks are about as happy as
they make up their minds to be."
- Abraham Lincoln