Ate breakfast and then 45 minutes later, dizziness, faintness, nausea, shaking etc. ambo came and took my blood sugar it was 3.9. why low after food?

Low glucose: You were clearly had hypoglycemia (h) and are not diabetic on medications. The possible causes of h, in your case are, too much alcohol, severe illnesses of the liver, such as severe hepatitis, can cause hypoglycemia. Another cause is a rare tumor of the pancreas (insulinoma) may cause overproduction of insulin, resulting in hypoglycemia. See a physician for help with your problem. Good luck.