I was taking cephalexin for a sinus infection a week and a half ago. I didn't finish the 10 day prescription only took for 5 days because I felt fine. This week I developed sinus headache, congestion, scratchy throat, very very bad sore throat with difficulty in swallowing, swollen tonsils, along with some green phelgm, mucous worse at night. I waited a day or two and throat felt worse, I started taking the Cephalexin again today. Should I take it for 7 days?