Did you have a brain MRI, LP or VEP tests? Any of these? It takes time for things to show up. I am glad your spine is clear.

I had a lumbar cyst that caused problems of extreme pain, numbness and tingling. Compressing the sciatic nerve and disk fragments from a herniation with splinters.

This showed up with a Myelogram with dye and followed with a CT while the dye was still in there. I have a EMG too. I needed surgery and was fine.

Just relax and hopefully the cyst in nothing, normal if not interfering with kidney function. I have a scar from a cyst on my lower left kidney pole. They scanned it with ultra sound, renal scan, other tests too. They can do other tests but they are more invasive.

I hope yours turns out okay. Good luck.