blood vessel lesions

I have had several lesions visible on an MRI scan for many years, this year there were more lesions so the doctor sent me for a spinal tap which also showed lesions. The doctor said that he is 99% sure that I have MS, but what confuses him is that the lesions also are showing up in my blood vessels, and he doesn't know what that is from. He started me on MS medicine, but has not said anymore about the lesions in my blood vessels.
I am concerned about the diagnosis. He said he could be wrong but if I took MS meds and it wasn't MS that it would not hurt me. but has not investigated any further about the blood vessel lesions.
I have been diagnosis 2 other times before with MS, and this neurologist didn't think I had MS. so I went off the meds in 1998. I have been with this Neurologist since then and trust his judgment, but I'm concerned about his own questioning now. What could the lesions in the blood vessels mean and should I be concerned? Thank you for considering my question.
Judy