I Used Some Expensive Bath Salts Exactly Three Weeks Ago..

I used some expensive bath salts exactly three weeks ago.. After two hours I came up in a rash all over my chest.. Since then various other areas have come up in spots. Now the spots have largely cleared up but I am suffering intense irritation all over my body - can this still be the bath salts or is it now another cause I.e medication and the bath salts are a red herring.