Eating healthier is giving me headaches!!

I just found out I’m prediabetic 😣 I drink soda every day there’s not one day I don’t ever drink and lately I’ve been increasing it by drinking 3 cans a day.

I finally decided to quit soda and start eating healthier, it’s been 2 days only and this is the longest I ever went on not drinking soda and drinking water only! But why am I getting headaches after I finish eating?

Is this normal? I have been eating vegetables and protein these 2 days.