What Causes Frequent Black Coloured Stools Along With Fatigue?

Hiiiii...from last two months I m having problem of loose motion and color of stool was black n i use to go nearly abt 4-5 times a day. One month before i had consulted my family doctors but his prescription didn t worked. Then I consulted an M.D. according to his advice I done sonography & doctor found tht I m. suffering from colitis. He prescribed me 5 days course of following medicines 1. Hyocimax plus, 2. Ceftas O, 3. Nexpro Rd. After taking this prescription I got some relaxation but still I use to go for stool for 2-3 times n color of stool was black n I lost nearly about 10kg weight. Then after the same doctor prescribed me 1. Rifastop-200(1-1-1) 2. Nexpro Rd 40(1-0-0) 3.Normaxin (1-0-1) 4.,Unienzyme (0-1-0) for 15 days after completion of this course color of my stool changed from black to brown but I use to go for stool for 2-3 time n bcoz of this I was having fatigue. After. Completion of this course he prescribed me 1. Normaxin 2.Nexpro RD 40, 3. Unienzyme for 1 month...do anyone of u suggest me ......do I m on the right track..?