My 15 year old daughter has Tricuspid valve regurgitation, nausea getting worse?

My 15 year old daughter has Tricuspid valve regurgitation. We have been experiencing consistent nausea with no vomiting with an onset of a headache be the end of the day. Usually the nausea lasts for 3 to 4 days. We have had this happened once in October for a week, then twice in November. However it has gotten worse in December. She has had nausea now for 7 days, however now she gets excessive sweating, fatigue, occasional sore throat, achy chest pains, arm pain, or back pain, and loss of balance. On the 19th of December she experienced hand tremors, bad chest and arm pain, and fatigue. I took her to ER, and they performed an EKG and xray on her heart, everything was normal. She was further diagnosed in ER with Rhumatic fever. Since then we have been battling the above mentioned symptoms, however its daily and to the point where she is missing school. Her pediatrician gave her Zofran for nausea but it doesn’t give any relief. Last time she went to dr. on January 3 she lost weight as well. Blood work as done to rule out thyroid problems and to check for inflammation from rhumatic fever. Blood work was normal. Her dr. feels the symptoms are due to migraine headaches. She does get headaches with the nausea but not every time. Can Migraines cause all these symptoms? Especially since they are now ongoing?