My 5yr Old Daughter Has Had Intermittent Fever For 3

my 5yr old daughter has had intermittent fever for 3 days and intermittent stomach cramps strong enough to make her cry. No diarrhea, no constipation, no headaches or any other symptoms we know of. Today we had her tested for strep throat and a UTI which both came back negative. At the Dr. office she did said her stomach was not hurting. Pain has been described as a squeezing in her stomach, centered under her belly button. O2 levels were fine today, Dr said lungs sound good and all visual exams look OK. I asked my daughter if she had eaten or drank anything that was not food or drink and she said no. Looking at her you can see in her face she is unwell. Her fevers have reached the upper 103's. We did not do a blood draw to test for bacterial infection yet. The Dr felt that would be the next test to run should my daughter get any worse. She was doing well most of the day, then this evening her temp spiked again and her stomach stated hurting again. We have been treating the symptoms with alternating Ibuprofen and Tylenol when they get bad. Dr told us to watch her closely this weekend and take her back in should she still have a fever on Monday. The stomach pains seem rather sever at times and have lasted long enough to worry me. I am wondering what other possible things could cause these symptoms. Dr felt the appendix was probably not the problem and as stated, a test for bacterial infection was the next thing to check. Is it also possible that this could be viral and that it may just need to run its course?