Feeling worse after third Tisabry infusion

Hello! F23, in May, I was diagnosed with multiple sclerosis, which first manifested in December after I had the flu, with numbness in my fingers, and then in April with blurred vision in one eye. At the end of June, I started a course of 5 methylprednisolone IV infusions to treat the initial onset (debut) of the disease. Then, in mid-August (after 2 months), I started Natalizumab (Tysabri) right away, a second-line therapy, since my MRI showed many lesions, and I was diagnosed with a rapidly progressing form

This past Tuesday (October 7th), I had my third infusion after a 4-week interval. However, last Saturday (October 4th), I played air hockey and afterwards felt like I had pulled a muscle in my shoulder. It turned out I hadn't, and since then I have felt all the symptoms of my old relapse: very intense brain fog, pain in my shoulders, neck, lower back, and legs, some blurred vision and numbness in my fingers have returned

I can't understand if this is my new reality now that the methylprednisolone has worn off—will it always be like this now? Or does this seem more like a new relapse, since it has been lasting for more than 48 hours (it's already been a week)? I'm scared that Natalizumab didn't protect me from a new relapse. Maybe it started flaring up when the methylprednisolone stopped being effective (after 3 months?), but the Natalizumab hadn't had time to start working yet (doesn't it take about 3 months to build up?)

I have made an appointment with my doctor for a consultation due to suspicion of a relapse, but the prospect of going through methylprednisolone therapy again seems daunting. I'm trying to figure out what is happening to me and I don't understand it yet. Has anyone else experienced this? I feel very anxious, the brain fog and my general condition are depressingly anxiety-inducing, so I would be grateful for opinions from experienced people. What do you guys think?