Itchy Doberman /Dry nails

Question
    I moved from semi-arid Colorado to the humid Memphis, TN area in July.  Everyone told me my skin would would improve in the humidity but my Doberman and myself are miserable with skin problems. I have problems I can treat with medicine but I'm at a loss with my Doberman.  About a month after our move she started scratching frequently.  Mostly her ribcage and more recently her nose.  She has sores (ulcers?) on the tops her feet but I think those may be more from her dragging her feet on the wood deck.  Her diet hasn't changed much except I think she been eating the small frogs I've seen in the yard.  I've also been giving her these OTC Brewers Yeast pills that contain Omega 3 Fatty Acids and garlic.  The bottle claims the pills are good for the skin.  I rarely bath her, usually just when she really needs it.  I can't find any evidence of fleas or ticks on her although I'm not quite sure what to look for.  My other 2 dogs (a Boston Terrier and a Border Collie mix) aren't having any of these problems.  Do you have any suggestions that may help?  Would bathing her with a moisturizing oatmeal (dog) shampoo be beneficial?
  Also, I notice her nails split easily. Can anything be done to help (other than regular trimming)?  
  Thanks for any help you can provide.  

Answer
In warm himid climates, there are many things that grow, like molds that a dog may be allergic to.  They walk on moist grass and carpeting and pick up the mold spores on their feet.  That makes them itchy.  If you cannot bathe the dog regularly to remove these allergens, then you can wipe the feet with a damp washcloth several times a day. You should let a vet look at the dog to see what is going on.  I'm sure that in Memphis, there are many vets who treat allergic skin disease.