Don't worry too much, we all have low blood sugar once in a while and can be for many reasons. Underlying infection, dehydration and stress to name a few.  There is a fasting blood glucose test that gives a better picture of what is going on, along with routine blood chemistry, liver and kidney function and cholesterol. I suggest that you ask your doctor if these are necessary, just for reassurance. Also, you should nat rely on just one test result, you need to test regularly and see if there is a pattern. Don't just eat sweets if you are low, a small amount of coca cola followed by a sandwich, crackers or brown rice will prevent it going high and then low again. 

It is very difficult to advise you without seeing you, you must see your doctor. Again, don't worry and good luck, JJ