I Was Recently Diagnosed With 'cellulitis' On My Lower Legs,

I was recently diagnosed with 'cellulitis' on my lower legs, and ankles. I took Apo Amoxi-Clav for 10 days and it seemed to clear it up, but I've been done the meds for a few days, and while I'm not entirely sure, it looks like the condition may be returning (some minor swelling, and 'discolouration'). I have a year old prescription of the same drug that I never took last year for a minor dog bite, and I was wondering if I could still use it, rather than going to see my GP, and getting a new prescription. I also wondered if it's wise to take anything before it becomes painful and inflamed again.