What causes white spots on fingernails?

I've been having really bad fatigue and other general malaise and haven't been able to pinpoint anything specific about what is going on to cause all of this.

I have several chronic conditions including chronic migraines.  I will find out whether I need a nissen fundoplication in a few weeks when I will speak with the doctor.

I noticed that my right thumb nail had a white spot near the middle of the nail bed on the left side.  The nail has since grown out some, so the white spot will probably be gone by the time I see my PCP.  My other thumb nail has a groove or pit that is like looking at a ditch on the nail bed.  One part before it dips into the ditch seems thicker.  The other part seems much thinner.  The groove or ditch is pronounced.

Both of these things on my thumb nails is new for me.  Having bad nails is not new, but this is new.

If I remember right, these things are caused by some kind of deficiency.  It would be helpful if someone could refresh my memory on which deficiency this could be, so I can ask my doctor about it.  Does iron deficiency cause any of this?  I have had iron deficiency anemia more than once and suspect I have that again, but I'm wondering what else is likely the cause of these unusual nail conditions.  Well, unusual for me anyway.

Last night I discovered some shallow pitting in another fingernail if that helps further in trying to figure out this mystery.

[Red_Star]

Zinc or calcium deficiency are causes of white spots on the nails.  Magnesium deficiency is a common cause of migranes (migraines). Depression large enough to hold a drop of liquid often indicates iron deficiency anaemia.

Zinc is essential for stomach acid production. Low stomach acid is very common. High stomach acid is not. If you are suffering GERD, don't assume you have high acid as low acid is the most common cause of this condition.

Low stomach acid for any reason is a cause of nutrient deficiencies.  Magnesium deficiency is the listed warning of acid blockers on the FDA website.

[Red_Star]

Zinc or calcium deficiency are causes of white spots on the nails.  Magnesium deficiency is a common cause of migranes (migraines). Depression large enough to hold a drop of liquid often indicates iron deficiency anaemia.

Zinc is essential for stomach acid production. Low stomach acid is very common. High stomach acid is not. If you are suffering GERD, don't assume you have high acid as low acid is the most common cause of this condition.

Low stomach acid for any reason is a cause of nutrient deficiencies.  Magnesium deficiency is the listed warning of acid blockers on the FDA website.