Hi, My Five Month Old Son Is On Cephalexin For

Hi, my five month old son is on cephalexin for strep throat and double ear infection. The first two doses he had I accidentally gave him five ml instead of two and a half ml. So therefore I accidentally double dosed the first two doses. Should I be worried? Do I need to take him to the doctor right away? I'm very concerned and don't know what to do.