Clindamycin
"I was prescribed this medication every 6 hrs for a severe tooth infection that was sore to my neck. It's been 3 days and the pain is subsiding a bit, very little heartburn, but I also am on prescription Prilosec. You cannot take any heartburn meds for 2-4hrs before and after taking clindamycin. My dosage is every 6 hrs. So far my worst side effect is the stomach cramping and I have the absolute worst metal taste in my mouth. Nothing seems to take it away. I suggest definitely following the directions exactly, especially with drinking water and NOT laying down for at least 20-30mins."