Why would i feel weak and shaky 3 to 4 hours after havin dinner?

Hypoglycemia: Some patients get a condition called reactive hypoglycemia which is due to overproduction of insulin. To avoid that condition take frequent small meals.

Could be low sugar: Need to get this evaluated. One possibility is that after a high-carb (refined sugars, white bread/pasta/potato) meal ur blood sugar is spiking causing a surge of insulin. The Insulin surge over-compensates driving your blood sugar too low resulting in ur symptoms. This is ofttimes called reactive hypoglycemia. Add to your diet: fiber, lean protein, olive oil, lemon, vinegar, cinnamon, spices.