Unlike paracet or brufen, amoxicillin can not be taken when ever you feel like.
Amoxicillin or any other antibiotic is taken as full course, let's say the course is 7 days even if you feel okay on day 4 it doesn't mean the bacteria is completely dead, continue to day 7 as prescribed by your Dr. Otherwise the bacteria developes resistance to that particular antibiotic, making it difficult to treat and we have very limited antibiotics to replace.
And, amoxicillin does not treat flueπ€