helicobacter pylori infection
"I hardly have any side effects (day4/5). One positive effect is that I am much more happy.  Not sure what or why. I did have a headache tonight and I felt kind of like I am withdrawing from caffeine.  (I don't drink coffee) 
Only one occasion of constipation a few days ago but ate a lot of fiber to take care of this.  Urine is darker than normal in the morning & that's with same amount of water a day, average 4 pint glasses per day.
This drug seems to have weakened parasite in gut, can't wait to get the other meds. I sleep well and no other side effects.  Maybe some subtle balance problems when walking."