It surely seems that the hospital is looking at the correct conditions.
All your symptoms appear to justify that this is an electrolyte problem, but hopefully they can give your a diagnosis very soon.

However, I am surprised that your potassium was only a "little" low.

Good luck.

Hi!
I've had similar symptoms on and off for eight months, been to nine doctors including a psychiatrist and a gastroenterologist. I've also been having racing heart (tachycardia), very bad gi problems, severe muscle twitches, sleep jerks (myoclonus), and sudden high blood pressure. Every test (and there have been a lot...) has been within normal ranges. Four doctors diagnosed stress, but the psychiatrist disagreed, and said there is an underlying physical cause. I've done piles of resaerch on the internet, and have this just week discovered that it is almost certainly a magnesium depletion, which has led to a slight potassium depletion. I drank very heavily for many years, which depletes mag. I also ate tons of phytate-containing foods, such as whole grains, soy products, legumes, sprouted beans, etc. Phytate binds with magnesium and prevents its absorption. I also stared a fairly intense exercise program last year, (which put a further strain on my reserves)right up until all this started. The thing about magnesium and potassium is that 98% is stored in tissue, not blood, so a standard blood test will show normal serum levels, while you are actually depleted. Magnesium is necessaryfor over 300 body functions. I stared taking 300mg of magnesium five days ago and already feel better than I have since august. Ofcourse, itis too early to tell, as the symptoms have been coming and going, but it is worth checking into. It takes about six weeks to replenish your magnesium stores, as your cells can only absorb and heal at a certain rate. Good luck!!