Eating fast food while pregnant

I’m 16 weeks pregnant and just recently every time I eat fast food my stomach IS NOT happy with me. I’ll sit on the toilet the rest of the day in pain because my stomach hurts so bad... Is this normal? I already made the vow to start packing lunches for work instead of eating out. I’m just curious to see if anybody else got sensitivities to foods while pregnant? Our little girl obviously doesn’t want any type of fast food.