What kind deficiency? I had a B1 deficiency for who knows how long that left me with Neuropathy like symptoms. Pretty scary Dr said I had starting stages Beri Beri symptoms. B vitamins are water soluble so they are excreted unlike other vitamins that are stored in fat supply of our bodies. Your Mother in law may need a Pacemaker put in. She mighy be having Bradycardia. Thanks Thomas
Shoulda have her ask the doctor about the electrical impulses to her heart. I have a friend that this was happening to and her heart was actually loosing it's electrical signal and therefore it was stopping. Just a thought. Good Luck.
I wonder if she has any arrhythmia? You will have to do various things to rule out what is wrong. Did they do an EKG? Getting a 24 hour heart monitor would be good if you can. Then there is the possiblity of iron deficiency. It takes a long time if you take iron pills to get normal again. Did they do a complete blood count? Iron level? Ferritin and B12? Is she bleeding anywhere such as from fibroids? If you don't know if her iron is low get the level tested as well as at least the hemoglobin or a complete blood count and ferriting and that will help to see if she is iron deficient. I wouldn't take iron if you don't know for sure as you can get iron overload and then it is very hard to get rid of. If they thyroid is low then she will be very tired but I haven't heard of fainting. The only other thing is seizure? Does she shake when faints or any sign of that?