You should really go back to the doctor to get the answers.
But one thing I can suggest, because I can see the impact on my own sugar levels, is cut out the bad carbohydrates - sugar, white breads, pasta, potatoes etc. If I eat a carb laden lunch, which I do sometimes for emotional comfort, I feel my sugar plummeting just a few hours later. I get shaky and feel faint and have a hard time concentrating.
I see OP that you mention your diet is mostly ramen...I personally would cut that out completely and focus on foods that have a lot of protein and whole grains, plus fruit and veg.
But having suggested that, again I will say, go back to your doctor and demand answers.