Thank you for the replies.
PSC - I have new running shoes 
I have tested this a few times as I am sadly a member of 2 gyms, one with life fitness machines and one with techno gym machines. The former doesn't cause any pain whatsoever. I used the technogym one after a few days yesterday and the pain is still there!
Seems like i'm going to have to stick to the gym that stocks life fitness machines. Shame really as i cant get to it as often as the other one due to pathetic commuting times to and from work.