From siboinfo.com a site that deals with small intestine bacterial overgrowth, a possible cause of RLS:
The bacteria interfere with our normal digestion and absorption of food and are associated with damage to the lining or membrane of the SI (leaky gut syndrome, which I prefer to call leaky SI in this case).
They consume some of our food which over time leads to deficiencies in their favorite nutrients such as iron and B12, which can cause anemia or chronic low ferritin..."
Chronic low ferritin. RLS is closely associated with ferritin levels. The gut HAS to have something to do with all this.