Hi Katie, it could be just weather or it could be that your blood sugar is yo-yoing. If you're eating too many carbs at breakfast and lunch, you might be experiencing some downs in the blood sugar. Are you monitoring your blood sugar during all this? And - please inform your doctor, too, and be ready to tell him/her what your blood sugar readings are during those times as well as what you're eating. Let us know what comes of this, ok?