I Have Not Had An Appetite For Over A Month.

I have not had an appetite for over a month. Im always tired and nausea. Was clear and foamy for about a week now its brown with strings to almost black. All i can keep down is water toast or applesauce. And im lucky if i keep that down. Tried ensure ect. Lost 15 lbs. My mom has gastro precious. Is that what i have?When i do feel like i have to poop maybe once a week and its liquid yet i Sit on toilet 15 to 20 min for one little squirt. Please give me advice. Thank you.