My hands have been cold at the tips of my finger nails. feels like frost bite sometime?

See your doc: I recommend seeing your doctor to rule out the organic causes.

Fingertip blood flow: This suggests problems with blood flow to the fingertip. Improtant information here is do you fingers chage color?. There is a condition where the blood vessels spasm with cold or even stress and can turn colors - white is classic and diagnostic and red blue can also occur. This can be due to underlying medical conditions or smoking (stop is you do) or blood clots- needs evaluation.