I too have had redness under my frozen shoulder arm. I saw my doctor and he prescribed a cream to use when it flared up. I've only used it a few times and it seems to have subsided. He advised to to use very mild soaps such as Dove and very mild underarm deodorants such as baby powder or Dove deodorant for sensitive skin. He told me to stay away from harsh and fragranced soaps, etc. He thinks in some way it could be connected to the frozen shoulder because I never had it before, and it was only under the side that was frozen. I hope this helps.