Vomiting followed by shaking/trembling

Patient: Last night I woke up with a horrible pain in my stomach and then vomited several times. Afterwards my stomach felt fine but my entire body was trembling and I could not stop shaking, and my heart was racing. I did not feel feverish, just shaky and uncomfortable from the rapid heartrate and some shortness of breath. After about half an hour it subsided and I was able to go back to sleep, but I still feel “off” today — weak and still a bit shaky / unsteady. What could this have been? I am currently traveling so not able to see my normal doctor.

Doctor: