Coal tar
dermatitis
"I've suffered from eczema since I was born. No plastic diaper cover etc. Born in 1960 doc's did a lot of odd treatments that didn't work. Finally, in mid 70's it went to my feet. My heels cracked also between the toes. The cracks were often over 1/2" deep, bled, & never closed. Of course the doctors declared that it was athlete's foot! I had to put a OTC solution that has alcohol as #1 ingredient! I couldn't walk in the mornings, bled on things, & was tortured by athlete's foot meds for years! 
Finally I was diagnosed with eczema & allergic to most trees, grasses, weeds, soaps, perfumes etc. Zinc oxide on the feet wrapped in a sock & plastic bag almost "cured" the cracks. Coal tar topical shampoos & face really helped too!"