Talk to Gastroenterologist on Stomach

I took antibiotic medicine (Agminton 1000mg) continusely 20 days 2 times a day, 1 tablet a time 5 years ago.I tried many doctors but no benefit. After that,I am facing stomach problems like black stool,loose motion,pain in stomach and when I eat something spicy problem is begin.but now since 5 months problems are continues like black stool,loose motion etc. Kindly reffer me a doctor who is proved expert for me.