What Is The Treatment For Itchy Rashes In The Arms And Abdomen?

I have been taking methotrrexate since november. 4 tablets once a week. also 2 mg ffolic acid, 2-600 mg caltrate plus d, 400 mg potassium daily. 50000 units vitamin d once a week. i started breaking out in december and continue to date to have itchy rash on arms, abdomen and legs. im thinking it is something im taking?