What Causes Itching And Dark Spots On Skin?

hai, I am simi, 27, 157 cm, 42 kg. I have skin allergy which started 2 years back when I took medicines for fever and cough. I had skin irritation, itching, redness, and becomes dark after some time. There is rashes all over my body now and heat is emitting from my body, so I have to take bath often. When I consulted doctors they prescribed paraffin liquid, calamine lotion, bethamethasone valerate, potassium chloride oral solution and tablets ranitidine, chlorpheniramine maleate, cetrizine. But I still have problems of itching when I go near to my dog or cat, or when I go out in sun. the dark spots on my skin has not gone. Could you please tell me what is the problem with my skin? What can I do to this dark spots? Is it due to cat bite (Because I have been bitten by my cat many time)?