Crohn's Disease or cancer ?

I'm a 21 year old female with no family history of colon cancer that I know of. Over the last couple of weeks I have noticed a number of symptoms; I have had changes in my bowel movements, so that they are occurring more frequently (3-4 times per day), but are not actually diarrhea, I have seen a small amount of blood in my stool twice but never any in the toilet boil or on the toilet paper, have had abdominal pain made worse by eating and on and off throughout the day, decreased appetite, some weight loss, small fever, fatigue, nausea, and burning in my stomach, especially when I lie down at night. Also some sharp pain in my lower back. The pain in my abdomen also moves around, sometimes its the bottom left, sometimes the middle and sometimes higher on the right. My left abdomen is tender to touch. I haven't noticed my stool become too narrow or stringy but it is smaller than usual. My doctor has ordered blood tests, which showed I have inflammation somewhere in my body but couldn't tell the cause, and my stool sample was negative for intestinal infection. Today I actually seem to be able tolerate food with less nausea and pain so I'm hoping a lessening in symptoms indicates a chronic condition rather than cancer. Any ideas?