Why has my virus come back?

I just got over a virus, not that long ago. I was on amoxicillin and mucinex. I finished both bottles, just last weekend. And, started to feel better. No one is sick in my family, and i have not been around anyone who is sick. I wash my hands 24/7, everytime i touch something. And, on Tuesday of this week, i noticed i was feeling a bit under the weather. My throat just hurt. Then i woke up today and felt worse, so i went into the docs office and i got extremely worse. My Bronchitis and Laryngitis came back. Why is it that i'm the only one in my family who keeps getting sick?