Have Constant Pressure Changes Messed My Insides Up??

I'm a shorthaul flight attendant and I usually do 4 flights a day, 4 times a week. Thats 32 pressure changes a week... I've been getting stomach aches and I can't go to the toilet (no2!) somedays during flying and for a few hours afterwards...it's like it's all backed up and plugged in there. I was sick awhile ago with severe stomach aches and was told by my doctor that it might have been gastroentirits. I was put on medication and with a week off work I was fine. I hadn't worked more than 2 days for a few weeks after that, but once I started flying 3-4-5 days i started getting similar feelings, even though they weren't quite as bad. For the past week I've had stomach ache and sometimes i get brief waves of feeling very hot and having shivers...