I m wondering about my sister in law. She s 58 and has a history of breast cancer to bone cancer to liver cancer with a most recent spot in her lung. She s been getting chemo but is a one month break. Yesterday she related to me that she did not feel good at all and last night vomited black, watery substance with black stool...I asked about any stomach pain or pain anywhere else. She said her stomach felt tight. I suggested she call her dr. They do not feel it is necessary...please advise. Thank you.