Can SVT And Mirgraine Headaches Be Related? My Niece, Age

Can SVT and mirgraine headaches be related? My niece, age 30, tall, thin, great health until about 4 months ago when she started having SVT, frequent PVC's, severe dizziness, neck tightness, high blood pressure with the SVT, defecation following the spells, and then headaches, severe fatigue. She has not had syncope, but feels like she will. Now, she is paniced that she will have an episode, and pass out while alone with her 2 yr old twins. All endocrine studies have been negative. Cardiology is looking at the SVT and discussing EP studies. However, no one is looking at these severe headaches that are keeping her in bed and making her feel so badly also.