M3 accidental withdrawal

So my last post was how I started intermittent fasting , well with that and school starting and my son working overtime , which means I go to get his girls and get them ready. So alot of running around in morning and I was not drinking as much diet coke (caffeine) as I had been prior to this new schedule. I think I drank 3 cans by 3 pm and yesterday and today only 1 and my head is border line headache. Groggy and I feel like that is the reason but I'm gonna stick it out and hopefully break this habit and drink more water !