--you've made it through the process with fairly minimal disruption.

From my understanding (admittedly gleaned from the spinal boards here and at Braintalk), the rubberylegs you're experiencing are exactly from what you mentioned; much of the purpose of the myelogram is to see if the increased fluid pressure will show in particular "collection" areas, signalling pressure on structures. In a normal spinal canal, the dye fluid should not "pool", at least not very much.

I'm hoping your rubberiness is temporary.

And make sure you tell us what both the spinal fluid and structural analysis show.