This would be related to proprioception which we don't seem to have any particular deficit of at least not according to any study I've seen so I don't believe a connection here is likely.  Also given my back issues I assure you I know EXACTLY where it hurts :) 

Proprioception which is our bodies awareness of it's own position in space is separate from mental visualization, this would be spatial visualization not directly related to aphantasia. People don't have many pain receptors in their body so what your'e describing is something that virtually anyone would have issues with.