You should talk to your rheumatologist about it. He/she will likely refer you to a neurologist.

I developed unilateral numbness and tremor in my right arm and hand last year and then started experiencing headaches, which I had never suffered from before. I take Enbrel. Because biologics can in rare cases cause an MS-like demyelinating syndrome, my rheumatologist sent me to a neurologist who ordered an MRI of my brain and nerve conduction tests on my arms. The neurologist also did bloodwork to check for B12 deficiency and a few other things. The MRI and nerve conduction tests were normal, but my vitamin B12 level was low. So the neurologist attributes my symptoms to B12 deficiency, and I now take B12 shots for that. Note that, as Banana said, when biologics cause a demyelinating syndrome, it usually goes away when you stop the medication.