If it's in your arse cheeks, it sounds like sciatica mate. I had it for about four months this year, it's a right twat. Starts off in your back, then your arse cheeks, then your thighs if it gets really bad. Goes as quickly as it comes though.
No mate it wasn't in my cheeks initially I've done that myself forcing myself to walk on it, that's just a slight strain that's self inflicted.
