Yep ,I,ve had that pain siatic nerve pain I think ,,But i,m a tough little bugger i find a good few laps in the pool in the morning heated as its winter hear and yeah definately a dencorub lina ment,is worth it.so m8 its probably the siatic nerve,and maybe action just a bit too deep,quite common,even for tjose guys who don,t fist ,hope that ok but as I said i find a good swim ,will normally do the trick with ,a good heted rub ointment.good luck m8,but if persisits see an oseopath .cheers reagrds rob