So since the high of yesterday I've been suffering with a nagging pain in my left hip. I've done a little online search and it seems I have all the symptoms of piriformis. I notice the pain after week 5, run 2 but didn't think too much about it. It didn't hurt whilst I was completing W5R3 but today has been pretty constant.
From my online searches it seems I need to start spending time stretching my piriformis muscle, so this evening I have spent most of the night on the floor doing the following stretch.
I can definitely feel it working - fingers crossed for W6R1 on Tuesday