Am i right in assuming this is a 'pressure' type of pain?
Heart burn is typically a sharp, burning, or 'stabby' type of pain that shots up the center of your chest, or sometimes in the area just under your heart... like where the top of your stomach would be.. Slightly to the left, just off center.
Its not uncommon for 18 year olds to feel anxiety, or stress - like legit stress, not just "oh i have so much school work, and a test coming up' like stress caused by actual worry. I have learned that even though you don't know that your stressed, you can be, so don't brush that off.
If it is happening ONLY when you HIGH sugars, its likely a form of heartburn, or potentially your body is being stressed, and this is the result. If it was a serious heart problem you would certainly catch glimpses of it while being active and when your heart rate is elevated.
Even if this is heartburn, its best to take care of it asap, if you let it continue as you get older it will get worse and more painful and your body will become more and more sensitive to food and drink :/
Heartburn is stomach acid slowly burning away your insides lol its no joke, try some antacids and see if it goes away next time.