Strep throat repeatedly?

Hey. I'm an 18 year old male.  

Two weeks ago, Monday the 7th I went to the doctor with a sever sore throat and was giving Augmentin to take for 10 days (twice a day).  My throat was really sore, I had a 103 degree fever, and thyroid glands were swollen.  Ibuprofen and Acetaminophen didn't do much to relieve the pain.   The rapid strep test said I did not have strep throat, but after looking at my throat a few times the doctor believed the test was wrong and gave me Augmentin.  

So after 2-3 days the symptoms gradually got better and life resumed. I finished taking the antibiotic on Wednesday (the 16th).  

Yesterday (Saturday) I started to feel sick again.  I slept most of the day with a fever and my throat is sore.  This continued overnight and into today.  I currently have on and off fevers, a swollen kneck and a sore throat (with bumps on it).

Is it common strep could come back like this?  Or could this just be a virus? Is there any concern this is something more serious?

Thanks