More lesions :(

Just had my yearly scan back, expecting to have a clean bill of health…but I have 3 more lesions :(. Consultant was very relaxed and said it prob happened during switch from Aubagio to Ocrevus. I was only off the drugs for 6 / 8 weeks! How do they know it’s not just Ocrevus not working :(. Lucky the lesions are in places where they don’t physically impact on me day to day (as far as I know) but it’s still brain damage so I am feeling fed up.