Suggest Treatment For Red-black Sores On The Arms

i am seeing a homeopathic doctor and seeking medicines for my skin problem. I have red-black sores developed on my arms, which are very itchy & unknowingly while I'm asleep during night I tend to scratch them & make them worse. My Homeopathic Doctor says I have Sun Allergy. I had faced th very same problem 8years back. That time this Doctor's medicine cured them, though the marks remained. Now its been almost 8-10 months & i have noticed no improvement in my skin condition & that's why I'm a little worried. I do not apply anything on the sores as it itches more & becomes worse. Please suggest.