Running fail

Went out for a 10-12km run today and felt good until at about 4.7km I developed what felt like a stitch. Walking completely cured it, until I ran again. Alternating between running and walking I got to approx 5k and gave up due to the inability to run at all. Maybe it was a stitch maybe it was something else, but either way it stopped the planned long run :( FAIL.