Do you think my filler could cause strep and react to amoxicillin badly. Will steroids help for both?

It is not likely that your throat infection and the swelling in your lips are related. However, I would suggest close follow up with the surgeon that performed the injection. Keep in mind that viral outbreak (like cold sores) may be provoked by lip enhancement injections, especially in light of your recent throat infection. Good luck.- Dr. Harmych

It is of some concern that your lips swelled long after the injection and you had strep without taking the full couse of antibiotics.  I think the most likely problem is that your lips got infected from the strep infection and you need further antibiotics.  You might need a second opinion.