What Causes Someone To Have Loose Bowels For Months? Could It Be Stress Or Cancer?

This girl I work w/ told me she has had loose bowel movements for 5months. What could cause that? She is under a lot of stress. Could stress do that? She wont go to a doctor because shes embarassed. Probably money too. ~~~~~MORE INFO. I only know a little. I wouldnt know this but she needs me to cover her tables at work. The 1st few times I thought she was smoking or calling her boyfriend. But she always goes into the bathroom. Sometimes 2 or 3 times a week, some weeks none. Some days she’ll go in there 3, 4, or 5 times a day. when I asked her if she was doing drugs, she told me no &then told me about the bowel thing. I believe her, she was really embarassed. I said it’d go away but she said it had been going on for 5months &only 2 or 3 times it had been almost normal ’stuff’.She said she’ll feel it in her stomach &has to go right then or she might not be able to hold it. Shes 20yro. Skinny. No drugs. Rarely drinks. Said she hasnt changed her diet but i dont know if she eats healthy . She skips lunch a lot.