Based on your history of gastrointestinal problems, I would not recommend
doxycycline.
Doxycycline works well but can cause sun sensitivity
and can cause esophageal reflux (~ heart burn or indigestion). Now, we are down to two choices. First, malarone (atovaquone + proguanil). Malarone is taken daily, begun one day prior to arriving in a malarious area, taken every day while exposed to malaria, and then for one week after you leave the malarious region.