Hi, my dear
I read carefully all your concerns, I am so sorry for your situation.
If I were your caring doctor, I would recommend to do upper endoscopy
- you have diarrhea
with black things (melena is suspected)
- you have already done the rectal exam and they had found blood is indicative of stomach bleeding
- your mother had ulcers.
Apart upper endoscopy, I'd recommend to take omeprazol 20 mg twice daily, drink more water, take iron and folic acid
All the best!