What you perceive as hard, fatty stomach may be bloating
of abdomen which along with frequent stools point out to Irritable Bowel Syndrome(IBS
)- a functional bowel disorder with no Organic cause but your symptom of extreme gain in weight points against IBS. You have not mentioned here about your Age, Sex, duration of symptoms precisely which have diagnostic implications. First you have to get yourself examined by a Doctor regarding your signs and symptoms for further evaluation... Take Care.