If your child still has fever after two days of being on the new, stronger antibiotic, you need to go immediately for medical attention again. Strep can be very dangerous as it can attack the heart or kidneys causing serious health problems. Never fool around with strep. If the kidneys become affected, the child may need temporary (and I emphasize "temporary") dialysis. Heart can develop murmurs due to fever and infection. A formerly common consequence of strep was that it would develop into rheumatic fever. Usually the antibiotics of today avoid that, if taken properly.