Well I knew something was going to happen sooner or later, it's been going too well!! Started out fine and did the first 10 minute interval with no problems. Started to feel a little funny on the 3 minute walk and when I started to run again, this pain arrived in my abdomen, like a semi-circle under my ribs pushing upwards. Never felt anything like that from running so tried to ignore it but by the time I was 3 minutes in I started to feel unwell and before you know it I'm doing a rather disgusting combination of running and retching which brought me to a complete standstill. Walked the rest of the way home trying to figure out what just happened! The pain has gone and I didn't throw up anything, just retching.
So annoyed I may well give this one another stab this evening. My legs feel totally fine. It's just weird!!