Have you been screened for diabetic changes? Have you had EMGs done? When you say "come and go", how long does it stay when it comes? How frequently does it happen?
Is this your only symptom?
Has your pcp/gp screened for vitamin/mineral levels? B12, D, magnesium, etc.? How about Lyme?
Did you read the radiologist's report yourself, or were you just told it was ruled out by your doctor? It's always a good idea to make sure you have a copy of the report for your records.
After ruling out those things, do your doctors have a plan to look elsewhere? Did you see a neurologist? If so, are they following up with you down the road?
Sorry for all the questions. There are a lot of mimics, so your doctors may very well be correct. If things have stalled at this point (i.e. no follow up with a neuro), then more details might give us some ideas.
No one here is a doctor, but some of us took some time getting to a diagnosis and have experience in the trenches of weird neurological symptom land :).