My Baby Is 2.6yr Last Monday He Suffer From Very

My baby is 2.6yr last Monday he suffer from very high fever so I take him to the doctor ,after check up he gav him ibogesic plus and zifi tab 50ml .his fever comesdown BT next morning his full body is cover wid red rashes and mouth too "gala under see pak gaya".plz tell me the reason.he not able to take proper sleep due to rashes bt fever is OK