Hi, ! I am sorry you are dealing with back pain following your treatment. Back pain is listed as one of the more common potential side effects, so what you are experiencing isn't unusual, but I would still mention it to your doctor, just to be safe. And he/she may have some suggestions for managing the back pain, so please don't hesitate to check in with your doctor. Also, fatigue can be a side effect, too. Here's some basic information on Ocrevus that you might find helpful. You probably have read this before, but I thought I would link it here, for your convenience -- https://multiplesclerosis.net/treatment/ocrevus-how-well-works-side-effects.
Also, here's one of our contributor's experience with her first treatment and I thought you might appreciate reading about her first side effects and how she managed them -- https://multiplesclerosis.net/stories/my-ocrevus-toe-dip.
I hope this helps and I hope your future treatments cause less side effects! Please keep us posted, if you feel comfortable doing so.
Best, Erin, MultipleSclerosis.net Team Member.