What Causes Itchy Rashes On Arms And Legs?

I am a 47 year old HIV positive lady. Have a sore on my right leg, that does not heal, it get darker (black) around it and I develop a rash only on my arms and a few on my legs. The rash doe not really itch and I don t want to scratch either. My one Dr says its Melesma, the other one says its Pinaculatus. The sore has been there for over 4 months now and the medication given does not help much. At firt I received Silvertone, then Clobetasol Propionate 0.05%. All along I have been given Netracort for the rash. It disappears and reappears. My 11 year old daughter is also HIV positive and gets Nevirapine and Norvir Retinovir 100mg elastic tablets. Now my Dr has changed her Norvir Retinovir to Kaletra 3.50ml once a day. What should I do as my Dr for my dughter does not explain to me why exactly he has changed medication. He makes it sound like my daughter is a guinea pig. He says: We need to test the new medicine PLEASE HELP!!!