Hi, !
First off, I am so sorry you are experiencing possible complications with your MS medication. Secondly, don't ever feel the need to apologize for any misspellings that may occur, as English isn't your first language. As an American, I am constantly amazed (and more than a little humbled) by the amount of people who speak and/or write more than one language at any level of proficiency. We Americans could take a cue from our global neighbors and try to learn more languages to fluency.
Okay, all that said, if you feel your medication is not working well with your body anymore, you first step is to talk to your doctor about this. It's (unfortunately) not unusual for one's body to just reach its limit with any given medication, even if it appears to be helping with lesions. Some medications used to treat MS (including Natalizumab) are just so strong and the human body just reaches a tipping point and can't endure anymore. And you know your body best. If it's not handling the medication well anymore, it may be time to look at other options.
I know it's incredibly disheartening to feel like a treatment is *finally* working, only to realize that a change might be needed. The good news is that there are other treatments that can be tried.
Please keep talking to your doctor and feel free to ask for testing to be done to make sure Natalizumab isn't negatively impacting your overall health. That said, whether the lab work comes back negative or positive, only you can decide whether or not to continue with Natalizumab. There's definite pros and cons to be weighed, but you deserve to have the highest quality of life possible and that's something to consider.
Good luck and please know you are not alone in this! Many of our community members have had to switch meds for all kinds of reasons (including their bodies no longer responding well to those medications). I thought you might find this article (and the many member comments at the end of the piece) interesting -- https://multiplesclerosis.net/living-with-ms/dmts-wish-known. While it doesn't speak directly about your medication, it covers the topic of DMTs and changing treatments. I hope it's helpful for you.
Best, Erin, Team Member.