Strep Throat came back?

Patient: Hello, my 7 years old son had a strep throat 2 weeks ago. We treated him with amoxicillin for 10 days. In 4 days he said that his throat hurts. I looked into his throat and saw light white spots. So is it a strep throat came back and we need more antibiotics? And one more question – is it ok to go to a pool when you are taking an antibiotics?Thank you.