Every time i get a cold it leads to a sinus infection and every time they give me amoxicillin, this happens 1-3 times a year. ive seen an ent and they did ct and no blockages. why do i keep getting these infections after a cold?

Vast majority of sinus infections are either caused by allergies or by viruses. Amoxicillin more or less useless (but it does make the doctor feel better). Either you’re being repeatedly exposed to viruses (kids, grandkids, school teacher, etc) or you’re smelling the pretty flowers in the front lawn too often. If multiple times/yr, Allergist may be more helpful than ENT