Muscle twitch in upper abdomen?

Recently I've been having some random muscle twitching in the center of my upper abdomen right below my heart. It mostly occurs when it feels I fully exhaled and am very calm and am in a focus with slow breathing. I'm 19 and in very good health. My only problem is I suffer from anxiety which may be a cause of it. At first I thought the twitching was a palpitation of the heart but it appears to be too low to be a palpitation. It startles me like a palpitation though and keeps me alert. I've had no problems breathing and no others problems. I used to drink a ton of soda and caffeine but am currently on my 4th day of no caffeine at all since caffeine makes my anxiety worse. Does this sound serious or a part of anxiety?