I have serious stomach sensitivities. There are a lot of Skratch products (skratchlabs.com) that are vegan and pull me through distance races without any gut issues. They have great electrolyte drinks (with or w/out caffeine), energy chews and bars. It sounds like you need to add an electrolyte and more calories at a minimum. There are also other completely liquid vegan products like Ucan where you don't eat anything else with exception of adding salt.