Biaxin and once in the morning

I was prescribed the XL 1000 mg for bronchitis and sinus infection. I immediately did searches on this medicine before taking it because I hate taking meds. Well I read some of these and IT FREAKED ME OUT. I needless to say still took it but instead of taking it all at one time. I take it once in the morning and once at night. It is giving me headaches I am pretty sure but it could be the sinus too. It messes my stomach up too. It makes my mouth really dry for a while after taking it too. I have noticed a few heart palpitations too, but I am very prone to having them. I am supposed to take it for 10 days but I might just hand in there for 5 days with it. Reading these messages SCARE ME TO DEATH. Then of course I think that we are a few out of thousands that probably do fine on this medicine. I bet every drug gives certain people side affects?? I HATE BEING SICK. I wanted him to give me the Z pak but he said biaxin works better and more for a sinus infection than z pak.