Hello, Welcome, and thanks for sharing your concern I went through your query, and I feel, your platelet count and sugar level are normal limit, the black spots could result from drug reaction, but usually reaction spots are itchy, which is not in your case, there is a possibility of such rash due to RA itself, and this will need management, if your rheumatoid doctor is not able to help please see a skin specialist for this concern of yours. He will surely help you I hope my advice would have been useful, in decision making regarding your treatment, still if you have any clarifications or doubts feel free to contact back. Thanks.