What's causing my mom to have health issues concerning her stomach?

Hello.

My mom is have strange issues with her stomach lately it seems. At least, that's what it appears to be. The symptoms appear completely out of random. She feels like she has nausea, and before you know it, she is in the bathroom vomiting. From what she described, it feels like a certain pressure slightly above her belly button, and right below her thoracic cage, kind of like below her heart. 

Last time we went to the doctor, she didn't have any heart issues. She had a glucose level that was a bit over the limit, but nothing particular to worry about. 

Another thing I've noticed about her is that it sometimes take her a long time to go poop, like 2-3 days or something, and given the bathroom is within earshot, it sounds like her poop is more of a diarrhea than your regular solid chunks. 

She just got out of the toilet now (she vomited), and she said that she has a headache as well as an earache. What could she possibly be experiencing? What possible illnesses could she have? We all eat the same food, so if it is food poisoning, it would have been evident by now. But from the looks of it, she's the only one affected. Can you please help me out? Of course I'll take her to the hospital for checkups but I need to know your opinion on what this could be.

Thank you