Treatment For Infected Toenails

Ok , I had my feet frost bitten into an unfortunate accident but I somehow managed to heal them. After few weeks or so , my toenails started to exfoliate badly , and they obtained this awful yellowish colour.The worst part is that the nails are falling apart whenever I cut them and they are very sensible , I can almost feel my skin .I'd been advised to use liquid vitamin A but it did not worked.What should I do?Is there a remedy for this?