Improper stool motion. Material!

This started after eating outside food one night. All friends who ate with me, also had upset stomach, but for me it was slow and more intense. Had to visit toilet within 2-3 hours of eating food, 3 a day, and stool seemed to contain undigested food, and was little dark and slightly foamy. On suggestion of a friend (radiologist) took omeprazole, which reduced a bit, but anything other than curd rice or stopping medicine, brought back symptoms. He suggested a doctor visit, but meantime doubted h.pylori and asked me to take lansoprazole 30mg, clarithromycin 250mg, and amoxycillin 500mg therapy a week. This helped reduce symptoms a lot, and stool is regular (once a day, in morning). But, having very loose & watery stool, dark in color and undigested material