I agree about calling your doctor and letting them know that the antibiotics are not working.
HOWEVER, if you feel as if you are getting worse - i.e., real difficulty swallowing, difficulty breathing, high fever, shortness of breath,unable to eat or drink, etc., then I would definitely get to an ER - but DO NOT drive yourself!
I also do agree about being tested for mono - it's a simple blood test. They may want to do another strep test at the same time and perhaps another swab that they can send away to a lab and have it cultured to see exactly what bacteria or virus is going on. this would definitely help them to be able to treat you appropriately.
If it does turn out to be mono and there's no active infection, unfortunately, there's not a lot that they can do other than give you meds to make you as comfortable as possible (antibiotics typically don't work on mono itself because it is caused by a virus and not a bacteria) - treat the sore throat with perhaps numbing liquids or sprays, tylenol or ibuprofen for fever and body aches. If it's mono and severe enough, they may also put you on steroids for a short period of time. When I had mono, I had a NASTY case of it - ended up in the hospital with a 105.6 fever when I arrived that went up to 106.3. They had me on alternative doses of tylenol and ibuprofen that would bring the fever down to 103 for about an hour and then it would shoot up again. So they started giving me prednisone and after about 4-5 hours, the fever started breaking and was completely gone in about 8 hours. The steroids also helped with the swelling in my throat.
I would call your doctor's office as soon as you can and at least let them know that you're feeling worse even with the two different antibiotics.
Strep throat is confirmed by a test when they swab the back of your throat. I can't comprehend any doctor treating you for strep throat if they have not tested you for it. If the diagnoses has been confirmed and you are not responding to the antibiotics you mights need something stronger. You should call your doctor's office and let them know how you are feeling. They would be able to call something else in for you or might want to do other tests to confirm what may be the problem. There are very resistant strains of Strep out there.
Have they tested you for mono?
I can't be sure that that's it, but if it is, mono can last at least a month. Strep throat is a common symptom, as is fatigue.
I would suggest going to the ER to find out.