Hello, I can understand your concern for red patches along with rheumatoid arthritis. After reading your query it appears that you have developed Vasculitis causing the red spots. This basically caused by inflammation of the small blood vessels in the skin which can be triggered by multiple factors. As the inflammation progresses the chemical inside the white blood cells is released to cause the kind of rash which you mentioned. There can be multiple factors producing this condition which are included in day to day life and some times it is really difficult to find one exact cause. I suggest you to meet a dermatologist and go for complete examination fo the skin to give you proper best treatment. You can apply steroid creams for the early resolution of the lesions and liberal moisturization. You can take oral anti histamine like loratadine or levocetrizine under medial advice. For the pain part you can take any pain killer round the clock basis. Do not scratch or rub the skin as it can lead to further aggravation. Despite above measures if the problem is not getting better then it is better to consult a dermatologist for best guidance. All the best.