Hi Mikaela, and welcome to the board.
I’m so sorry you’ve been really going through it. I wholeheartedly agree with Gretchen about getting a second opinion. If you can see an MS specialist, that might be particularly useful. You can get a list of local MS specialists by contacting the National MS Society.
Over the past few years I have had neuros go back and forth over whether I have CIS or MS, as I too only have one lesion that shows up on MRI, although I have additional issues and abnormal signs that lead them to believe I have other lesions. It is definitely frustrating and scary to be sick and not know for sure what is going on. Keep on searching, and feel free to post any questions you might have. This is a great place to come for information and support.
Here is some info on lumbar puncture with fluoroscopy...is this the one you meant Gretchen?