Most probably you are suffering from allergic dermatitis. In these allergic diseases your body becomes highly reactivate to allergens. There are several homoeopathic medicines apart from urtica urens like Arsenicum iodatum, Histamine, Dulcamara,  Natrum muriaticum, Calcarea carbonica, Sulphur etc. Please consult one homoeopathic doctor before taking any medicine for real impact.

You are suffering from irritant contact dermatitis. Allergies are mostly caused by a hypersensitive reaction of cells in your immune system. This is not a local ailment but a general one. As a person too you are too sensitive I believe. You cannot treat this by just suppressing the expressions on ur skin with topical solutions instead treat the cause. Please consult a homoeopath who will treat you from within and help you get down this hypersensitivity.