Caffeine & Pregnancy

Ill be 20 weeks(2nd pregnancy) Sunday & I know how vital water is when your pregnant I drink it faithfully! But I do have cravings sometimes I may want a sprite to go with certain food, the thing is when I have that one cup of sprite out of all the water I drink, why do I have to pay for it with a MASSIVE headache? Is it the caffeine? When i drink juice or even gatorade it doesnt bother me at all. But one sprite literally sends me into a episode of non-stopping headaches!!

Update** A scientist commented & said Sprite didnt contain caffeine & i googled it & they were absolutely right! So i guess any soda gives me a headache then. It also happens when I drink a coke! Literally any soda!