I Started Taking A Viral Tablet For Cancers In The

I started taking a viral tablet for cancers in the mouth - Acyclovir - within 1 1/2 days of taking 4x/day; I started getting a sore throat & slight cough, It continue to get worse - felt like sinus infection - running nose, and sl. fever. I reduced the pills to 3, then 2 then quite - aches, fatique, headaches, bad sinus! I quite for 2 days - am I having an allergic reaction to it? I restarted @ 3 pm and now I have headache and sl fever and extreme fatique again!