Almond butter seems to work okay or frozen blueberries with yogurt and granola.  I always keep a few pieces of hard candy with me and I basically switched to eating smaller snacks throughout the day as opposed to larger meals.  I am very cautious about sports drinks...they can be unsettling to the stomach and some cause sugar spikes.  Try mixing a little bit of honey with bottled water or carry glucose tablets with you. 

Also, increase your protein and fiber intake and combine it with moderate carbs and healthy fats.  Usually, I have beef jerkey and pretzels after long runs, for example, and I also eat a lot of fish (especially salmon and tuna).  Of course, try to limit any refined flour or sugar products because the type and overall digestion of carbs makes a big difference.

It can be a tricky condition to manage, but make sure you always have something with you (carbs & fat) that you could eat quickly if necessary.  Really, even peanut butter crackers would be fine if symptoms came on quickly. 

Wishing you all the best!