Fingernails discoloration

Around three years ago, I mashed my left thumb at work. This caused the fingernail to bruise and eventually come off. However, it has never grown back right. It has yellowing underneath the nail, like a fungus which the dermatologist tested for and was negative, and whiteness on top where the nail looks dead, and you can see the new nail underneath. The doctor didn't think I had damaged the nail bed because it was growing out straight, but is funny looking. He prescribed a urea nail stick to aid with the fungus like matter under the fingernail. I keep it trimmed back to allow for new nail growth, but it gets to a certain point and develops this gross looking end to it. Any idea why it's taking so long for the nail to regenerate, or is this an indication of a possible underlying cause?

[Vanessa Lacuesta]

Hi

Dead nails lead to underlying fungal or bacterial infection. The dead skin underneath may thicken and this may hamper normal nail growth. This may take quite sometime to restore your nail back to its normal appearance. It may take months. It is best to maintain close follow up with your doctor. If fungal infection is present , the nail may detach from the  nail bed which is not true in your case. So give this quite some time. Do not forcibly manipulate the nail to avoid injuring the area.

[Mhutch7338]

I am seeking advise and information.  I will try and make this short.  My 7 year old daughter finger nails and toe nails are turning black and are seperating from the skin.  I took her to a determologist and he really could not come up with a diaginosis or reason why this is happening.  He ran some test of the nail and it came back negative for fungus.  It appear to be spreading to other finger nials (so far 3 finger nails).  He prescribed some cream to reduce the thickness and it appears to be working, although, keeps speading.  It is now starting to showing up in her toe nails (4 toes).  Any answers on what this might be and any advise on what test or other doctor I can see to pinpoint a diagnosis?

Thnks
Mhutch