For temporary relief from widespread itching, you can take an over-the-counter oral antihistamine (like Cetirizine 10mg once daily) and apply soothing Calamine lotion to the affected areas. Avoid hot showers and try not to scratch, as scratching worsens the marks and increases infection risk. Because your symptoms are severe, widespread, and leaving spots, they could indicate an allergic reaction, hives, or another underlying skin condition. Please consult a doctor or dermatologist immediately for a proper diagnosis before using any strong prescription steroid ointments, as the wrong treatment can worsen your condition.