I just got done with antibiotics for strep throat on tuesday and since friday i started with strep throat again. could it be that they didn't work?

Possible : It can sometimes take more than one course of antibiotics to eradicate strep .

Strept throat: If the recurrence is definite then it would have to be that the antibiotic was not good enough, you may have to be placed on a different antibiotic for a slightly longer period of time

Maybe/not: Strep A is universally killed by the penicillin family of drugs.Some of the others have less success.Persistence of pain or symptoms after treatment can be due to co-infection by viruses (mono) or you can become re-infected from re-exposure.Some think the irregular surface of the tonsils and nearby germs act to shelter enough strep that it could start over.A second round of meds may be needed.