I am suffering from red rashes on my shoulder. what cream should i apply ?

Depends: One has to know what the diagnosis is. If it's an allergic reaction to clothing(contact dermatitis) a cortisone type cream would help. If it's a fungus infection an antifungal cream is indicated. If it's a bacterial infection(cellulitis) an antibacterial cream like bacitracin is needed. See your physician or dermatologist for diagnosis and treatment if your rash persists.