Hi ! From the description of the symptoms, it seems that you had a food poisoning which can mimick the pain of appendicitis
and hospital doctor also got confused initially. Appendicitis is mostly a clinical diagnosis, and the doctor rightly discarded this diagnosis after examining the patient.
The dizziness could be diue to fall in blood pressure due to dehydration
or due the feeling of nausea. The doctor might have given a course of antibiotics for your abdominal pain
You have not mentioned your marietal status. If you are married and not adopting any contraceptive
methods, then you might have landed in an ectopic pregnancy which left you faint and dizzy with a low blood pressure. For this you should also obtain an ultrasound of your belly immediately.
The third possibility is a pelvic inflammatory disease
which might give rise to lower abdominal pain. For this also you should consult your gynaecologist. I wish you a early recovery. Thanks.