Hi there! I've just done a pedicure assignment with a very similar question actually! I would say that non-medical nail and skin disordes could include:
severely bitten nails - onychophagy
overgrown cuticles - pterygium
very thick nails - onychauxis
longitudinal ridges
beau's lines - (although can be caused by illness)
bruised nails
Not sure if I've helped at all, but thought I'd add my two penneth!
We had to list 3 nail & skin diseases and 3 nail & skin disorders. I used very thick nails, psoriasis and bruised nails for disorders, and for diseases I used athletes foot, wart/verrucas and paronychia.
Good luck! xxx