ill for weeks..anyones advice greatly appreciated!

I started feeling groggy about 2 weeks ago. Tiredness and sore throat. Went to docs after a few days who said it was pharyngitis. He gave me penecillin. Unfortunatley, the antibiotics didnt work. I went back a week later and he's given me a swab test for my throat and more alternative antibiotics. This was 5 days ago. Throats a lot better but comes on and off, but im feeling really rough now. Exhausted, groggy,aches, anxious. The swab results from my throat came back as clear (im not entirley sure what he would have been testing for?) but im still feeling rough, worse than when it first started.  Sleeping 10 hrs a night, lots of vitamins, good meals but to no avail. Need to go back to work this week but even the thought of it is exhausting. Any ideas??? Please help