Maria, I'm so sorry to hear about your BIL. That's horrible and I sure can see why you are stressed out. The best we can do is pray for him.
Many with fibro have thyroid issues. I'm checked periodically. I showed that I had hypothyroidism but after a recheck I was fine again. But, do see your doctor about that. There are medications that can help and you will feel better if that is what is going on.