MS or LYME

Daughter went hiking in Scotland three years ago. about 3 weeks later she started vomiting at night ( early AM) 3-4 nights a week. This went on for 3-4 months. Then stopped and she developed recurrent: nausea, dizziness, fatigue, numbness in limbs and blurred vision. (listed in terms of frequency). She has an eroded esophagus and takes Zantac. She has periods of normal health ( 20-30 days) and then 2-4 days of illness. We have seen a number of doctors: Neurologist, gastrointestinal specialists, infectious disease, psychiatrist, sleep Doctor, education specialist etc with no diagnosis. All CBC are normal, she does not have h pylori. We recently had a LYME test done and it was ELISA positive but the Western blot was negative with only on one band at 58. Any recommendations how to proceed? Does it make sense to follow up with a IGX test for LYME? Could this be MS?? If this is MS are the recurrent periods of illness so short? What diagnostic test could help differentiate? GP want to follow-up with a look at rheumatoid factors? She does not have a rash or any arthritic symptoms. ANY suggestions ??