Nail Problems in Dog

I have two German shorthair, blue healer mix . They are litter mates about 1 1/2 years old. They eat very healthy food, and live an active life style.
One of my dogs is having a nail problem. His nails are starting to crumble. The black exterior comes off first them it leaves a mangled white nail left. One has broken off almost completly, he has two more that are just starting to become painful. He will keep pressure off of his front paw. We have tried everything. My last resort is I was told to feed him fish oil. Or large doses of omega 3.
I feel horrible. He is in pain, his nails are falling apart and I dont know how to help him. While his brother is perfectly fine.
Doyle has had all the problems. From ear mites to anal gland problems. Does anyone know what could be causing this, and or how to help him or at least make him more comfortable?
I should also add, he is not a digger, nor a jumper, so I dont believe it is self inflicted damage.
Our vet gave us antibiotics but they are not helping.

I heard that gelatin makes nails stronger, but I have no idea how to administer it or if it is possible to give gelatin to a dog, or if it works on dogs at all.... Do you keep the nails short? What about boots? They might help protect the nails.

Their nails are trimmed, I take them to my dads, he has a small farm and he does it for me. I have never heard of boots, are they actual shoes for the dog? His back paws look to be fine it is only his front paws that are losing toe nails.

Yeah, they're soft material and leather boots. We have another thread going on about them right now: http://www.pets.ca/forum/showthread.php?t=21621

Thanks,
I will check them out.

You may also want to check with your vet about adding Biotin to his diet (it's a B complex vitamin). Both of my dogs have taken it in the past, I used to add it to my horse's feed, and I take it too. It's helped between all the nail/hoof problems we've all had, but you'll want to double check on the dosage.

Could be a fungus but it could also be an autoimmune
disorder. May be a good idea to have it vet checked.

Thank you everyone.
I have made a vet appt. Was planning on it anyway, just wanted to see if anyone else had heard of it.
I will let you know what I find out.