Had this for years, along with muscle cramps in my feet- I couldn't put them in certain positions without horrible cramps, and then I started getting them in my abdomen just bending over, and nerve tingling and pain that moved all over my body, and a bunch of other symptoms.
For me it is something to do with either B-12, B9, iron, D or all of those. I had a doctor test my homocysteine level and it was high- so I wasn't absorbing either B12 or folate, even though my blood levels were fine. I take injections now and supplement methylfolate and a multivitamin. My ferritin was low, so I take iron, and my D was low. All of those vitamins work together. I had anemia although it didn't show up through regular bloodwork.
Now, I have no more tingling and nerve pain, no more muscle cramps, no more twitching! If it starts to come back, I haven't been taking my vitamins. I also had all of my other symptoms mostly resolve, which included blurry vision, poor night vision, seeing flashes at night, hair loss, dry ridged nails, yellowing and breaking nails, bluish nail beds, pale inner eyelid, yellowing and pale skin, insomnia, headaches, general queasiness and no appetite, joint pain, bone pain, skin burning, always freezing, exhaustion and some others. I thought I must have MS or be slowly dying.
I think estrogen hrt helps too, but the vitamins have made the biggest difference. I had everything checked and no idea why I don't absorb them well but since correcting things I feel a world of difference.
Could be something like that in your case too- usually muscle twitching like this is not caused by a degenerative disease, so try not to conclude the worst, and check on your vitamins and electrolytes.
