I need some additional information.
Are you having any chest pressure or tightness?
Are you diabetic?
Do you have any other illness?
Are you on any medication?
Any new over the counter medications or herbs are you taking?
How long has this been going on?
You could be coming down with the flu however, it really sounds like your blood sugar is dipping low. Sometimes when that happens and you eat your blood sugar will elevate but then drop again.
If that continues and you do not get ill with the stomache flu, you really need to see your provider. Another way to check is if you know someone who is diabetic and you can check your blood sugar when you are feeling shaky. Normal is approximately 80-100.
However being anemic can also have some of the similar symptoms. So really the best thing to do if it continues is to see your provider so you can have labs and an exam done.
Tonight if you develop confusion or chest pressure/pain with those symptoms, immediately go to the ER. Those symptoms could indicate a stroke or heart attack.
Thanks and best wishes.