Did the GP actually look in there?
The reason I ask is that, on the one occasion where I was practically sobbing at the thought of breathing and was drooling rather than go through the agony of swallowing, the doctor refused to look 'because it's just a virus'.
Really?
The 'virus' turned out to be three quinseys, according to the surgeon who nearly lost me on the table four years later - not only had the scarring closed half my airway, the infection was still present throughout my soft tissues, as he found when he began what he had thought was a fairly simple tonsillectomy.
I couldn't gargle for the pain and Difflam burned like acid (when it's not supposed to).
The pain you describe reminds me of how I felt on the day at the GP, so it might be worth making another appointment, especially if you feel as though your throat is closing up despite the antibiotics - it could also be that the antibiotics aren't effective upon that particular strain.
Or it's just going to take another couple of days - but I'd be wary just because of the longterm effects I had (mind you, the unplanned parts of the surgery changed my voice from generally out of tune and pathetic to a massive vocal range and precise tuning, so it wasn't all bad in the end...)