It sounds like fibromyalgia is the least of your problems. Sounds like you have had a heart attack! And those irregular heartbeats can send tiny clots into your brain to produce strokes or TIAs. That droopy eyelid and blurry vision sound suspiciously like a stroke to me also. Don't trust all the medical tests; it's probably worse than they tell you but will take years to find anything useful out so don't hold your breath. I've had a hysterectomy, a total pelvic rebuild 10 years later and have a slightly underactive thyroid; but those alone shouldn't be cause for worry.
Are you on blood pressure meds? Those can cause a slow heartbeat if you don't really need them or take more than you need. You are much too young to be going through all this! My heart irregularities and stomach issues were caused by a severe head injury that broke my jaw and knocked my Vagus nerve out of whack for several years resulting in bad headaches, heart arrythmias and miserable stomach issues not to mention several expensive dental treatments to fix my teeth for a dropping jaw.
Doctor's won't test for Vagus nerve problems unless you make an issue out of it; even then it's a crap shoot. That alone can really wreck havoc with your health! And, of course, insurance companies rule the doctors so their hands are tied in many cases.
I managed to diagnose my own issues watching U-Tube videos (10 years after the head injury) and drawing my own conclusions, putting it all together. Too little too late though. My stroke last year should have killed me but God had other plans for me. It was a total occlusion of the Basilar artery (only 1% of ALL strokes in the world are basilar). Today I do much less but am still able to cook, drive and keep house (somewhat). Life gets better as I continue to heal from the stroke. I hope you keep searching and learning how to help yourself because you know you better than anyone else!