Can a sore lower back causing erectile disfunction?

A few days ago my partner while in bed moved and got a sharp pain in his lower back and a tingle down his leg, thought nothing of it as it went.  The intermintant pain is getting worse depending on how he moves but it's still sporadic pain.  What he is most worried about is the fact that when he gets a twinge in his back it causes his penis to go soft instantly even when in use at the time. It definatly coincides with the pain and his pelvis area is a bit uncomfortable too.  With it being bank holiday weekend he can't see anyone till at least Tuesday and is very worried.  Could it be a trapped nerve, or does anyone have any ideas what has caused it and if it's only a short term side effect.