Welcome @lizbhere, I'm pretty sure you are not alone with being tired and getting a new diagnosis every time you turn around. You mentioned having arrhythmias. I'm wondering if you might find this post by @colleenyoung helpful in the Sudden PVCs with congenital heart disease discussion - https://connect.mayoclinic.org/comment/613990/. She has a link to an expert blog post and video that might be of interest.

– Congenital Heart Disease Arrhythmias March to Their Own Beat https://connect.mayoclinic.org/blog/congenital-heart-disease/newsfeed-post/congenital-heart-disease-arrhythmias-march-to-their-own-beat-2/

Mayo Clinic has some information on spinal cord tumors that may provide a little more information -- https://www.mayoclinic.org/diseases-conditions/spinal-cord-tumor/symptoms-causes/syc-20350103

Being a nurse, I imagine it makes it even more stressfull when you don't have all of the answers. Have you done any research on the nerve sheath tumors?