I have been experiencing that lately as well!! It's as if all my energy leaves me through the floor and I cannot take a single step more. I have also had trouble waking... I explain it to my husband using the metaphor of magnets. It feels like I have magnetic strips on my eyelids... I just can't keep them from slipping closed. Love and light to you; you're not alone. ❤️

Sounds like you all could get relief from CBD products . Have You tried them ? My doctors agreed with me about no drugs .
We have a plan that if I ever do want , then I have selected naltrexone because it has no side effects . Heavily researched at Stanford . Ask your doctors for it . All they hand out are the ones that have side effects . You have to do your own research
And not just take their word as to what you add to your body ! It’s YOUR body, not theirs !

I think I know how you feel. When things get too much, I feel like if I don’t lay down right now!-even if I’m out in public. I feel like I will die if I can’t lay down, I just can’t go on.

Oh goodness, yes! Today I just drove to a shop less than a km away, picked up a few things and suddenly felt hot, dizzy and so weak! I almost phoned my DH to get on his scooter to drive me home and when I felt better I could drive him back to his scooter! It's not "tiredness", I'm not sleepy, just weak as a newborn kitten! And I get irritated because I can't do the things I want to do and every little thing is a major effort! I wish I could tell you how I solved this, but I haven't a clue. {{hugs}}

All drugs have side effects, especially if you have something like fibro that makes you extra sensitive to everything. I have other issues that we treat hoping not to annoy the fibro too much.