If I Have Been Drinking 2-3 Large Dr. Pepper's A

If I have been drinking 2-3 large Dr. Pepper's a day (large from Sonic/McDonald's) for the last 30 years and in the last 3 days , only had (2) 1/2 of a large Dr. Pepper in the last 3 days, still drinking 2 cups of coffee in the mornings and 1/2 water 1/2 sweet tea during the day; could that cause a really bad headache for the last 2 days?
Thank You,
Shelia