You can buy a glucose meter on ebay for about $15 and try to keep a check on your blood sugar. Milk is a very good source for raising blood sugar, especially during the night as it doesn't 'wake you up' too much. You may benefit from drinking a glass of warm milk before you go to bed - or an oat cereal - such as an instant porriidge with a small amount of honey that should keep your sugar levels fairly even through the night. I've had low blood sugar for the past three years and the night is definately the worse time until you get it under control.
Get checked for hypoglycemia. It can be a very serious thing. At any pharmacy you can buy a bottle of glucose tablets over the counter. When you feel faint or weak, eat one or two, they are pure sugar and will be absorbed in the stomach. You will begin to feel better in under 10 minutes. Don't make this remedy a sub for a doctor's appointment.
You need to find a doctor and get some help. A doctor will be able to give you tests. Make a list of all your symptoms and when the symptoms occur. In this way you will be able to communicate your concerns clearly to your doctor. On average doctors spend only 15 minutes with their patients, so go prepared so you can use the minutes with your doctor to your best advantage.