Suggest Treatment For Severe Abdominal Pain, Fever And Severe Headache

I have a 6yr old female who had severe abdominal pain for about 7 hours. No vomiting, no diarrhea. Highest temperature was 101.6 but was brought down with Tylenol. Took her to the local ER where all blood tests came back perfectly normal and her pain had subsided finally. The next day, after she woke up she had a severe headache. No more abdominal pain but a low grade fever never going above 100. Her headache lasted all day. This morning she woke with a severe headache which was treated with motrin and then she went to a primary care physician. A neuro exam was performed and all was normal and the headache was gone as well. The headache stayed away for 7 hours and suddenly came back and was quite bad. It faded for about 15 min only to return even more severe. Now, she is laying down in a dark room after taking motrin again. Please help me figure out what to do to help her.