What Causes Stomach Cramps And Diarrhea?

Hello, My wife has been sick with severe stomach cramping & diarrhea for 1 solid week today. She had given a stool sample that revealed an abundance of white blood cells, so they said it appears her body is trying to fight off something in her intestines or stomach. Her GI Dr checked her out Wednesday & told her it is not her Ulcerative Colitis flaring up, they think she has a virus or bad bacteria wreaking havoc in her intestines. She has given blood sample, stool samples, and is taking all kinds of medication with no sings of getting better, & she has reached her breaking point today. Is there any reason bloodwork should take more than 2 days to reveal what may be present in her body? Is there anything like this virus or bacteria going around right now in the U.S., or should we take her to the ER? She cannot retain water or food very long, and the meds are not helping her with the pain very much. She is dehydrated, fatigued, and has missed work all week to stay in bed & the bathroom. Any insight or advice would be appreciated. Sincerely, Steve