Hi thanks for your question.
Yes this could be
keriorrhea.The type of food your taking that is canned tuna fish, which contains only protein can produce keriorrhea. Your diet doesn't contain any fiber content and carbohydrates which very important for binding the stool. Feeling of
tiredness could be due to lack of carbohydrate in diet as carbohydrates are the main source of energy. Include small amount carbohydrate and plenty of fiber in your diet in the form of fresh green leafy vegetable and fresh fruits which will besides binding the stool ,will also provide energy to your brain, as brain cannot use anything other than carbohydrates for energy.
Hope this answers your question