There is no clear relationship between multiple sclerosis and chronic myeloid leukaemia (CML), a type of blood cancer characterized by rising leukocyte count. There are some case reports where MS has been induced in patients taking certain types of drugs for the treatment of CML and vice-versa. Please get a complete blood count and a peripheral smear examination done. Her treating doctor would be best placed to examine her and exclude a cause for the rise in the cell count. In case the total leukocyte count continues to rise, you will need to consult a hematologist. A bone marrow examination (including cytogenetics or molecular analysis) may be warranted.