I Have Rheumatoid Arthritis It Has Been Two Year Diagnosed.

I have rheumatoid arthritis it has been two year diagnosed. Yesterday I noticed ring shaped little blister on the palm of my hand now there on the other palm of my hand 7 on my right hand and under my right arm. Any idea what this is ? Also
I have been married for 20 years. We are faithful people, so it is not std. I am taking remicade for almost a year. I realize I do not have an immune system. thank you.