The excessive mucus is most likely due to the viral throat infection. Such viruses seldom respect boundaries and limit themselves, for example, to the throat. They frequently spread from the throat to the nose and sinuses; less so, to the ears. Unfortunately, the same can be said of many bacterially caused sore throats, including strep. If caused by a virus, as you suspect, once you note improvement that should quickly proceed to complete resolution and, with that a progressive reduction in mucus production. On the other hand, if the excessive mucus persists, that could be a sign of bacterial infection and an indication for antibiotic therapy.