I read up a little on Myotonia Congenita. (I knew I had heard of myotonia before). That your father had it could make it possible for you to as well, though more likley the autosomal dominate form which isn't supposed to affect heart or digestive muscles... which I'm sure you've probably already know.
What blood tests have you had? anything other than standard tests?
Such as - blood sugar, including for insulin resistance (not usually tested for on standard tests). Thyroid and other hormones - you need more than just TSH tested, have them check free T3, free T4, and for antibiodies (check the thyroid section for more information on tests). Even standards on accepted TSH levels have changed in the last few years, so you should have that all rechecked.
Have you been fully checked for vitamin and mineral problems? Magnesium isn't usually checked but can cause issues.
Your "spells" sound a lot like how I feel before a near faint, I have neurocardiogenetic syncope. NCS can include problems with slow heart rate - bradycardia. If you're being woke up often by the feeling that your heart rate is slow or stopping you should see if you can get a holter monitor to wear for a few days to try to catch what it happening.
You may also want to look up postural orthostatic tachycardia syndrome, may not be likely but both do have stomach and digestive tract issues with them.
Have you been cleared of possibly having a mitral valve prolapse? That can cause some people weird symptoms (MVP syndrome), too.
The problems from your gas/stomach upset could be that irritating the vagus nerve - which will affect your heart rate. That happens in just about everyone, that's why people sometimes mistake acid reflux as being a heart problem. Vagus nerve problems can also cause gallbladder issues - such as in my case it will cause it to release too much bile at times.
... Just noticed your location.
Good luck and I hope can find the treatment you need without traveling out of state.