Bashed nails are just part and parcel. Lost count of how many I have lost. Mother nature treats em best. If you have a partially detached nail and you want to run, just bind it with zinc oxide tape. In fact, zinc oxide tape is a must have in any fell runners kit bag. It has almost mystical properties.
I got a mahoosive blister on my heel last weekend. went right into the instep. The treatment is just to put zinc oxide tape over it. It makes walking painfree and when it falls off after a week or so, more often than one not, the blistered skin has magically blended back in. I swear by the stuff. If you are blister prone just stick it on before you race.