My 21 Months Old Son Had Fever We Gave Him

My 21 months old son had fever we gave him maftal p 6 ml at 6 pm his temp came to normal took him to doc doc priscribed anti biotic at 12 midnight again he had temp about 100 f he vomited immediatly his temp was not coming down so we gave another dose of 6 ml wit in an hour just worried if it is safe