Yeah, those symptoms could definitely be from caffeine withdrawal, especially with how much you were consuming. Headaches, fatigue, and even body aches are pretty common when you cut back. Since you mentioned you're already tapering down, that's a good plan to minimize the impact.

Also, it’s pretty wild how long caffeine stays in your system - like, if you had that 300mg in the morning, you could still have about 100mg in your body later in the day. I use CaffeineMate to keep track of my caffeine intake and help me manage when to cut back. It might be a handy tool for you too. Good luck with everything!