Went for a run, instant very painful stitch

[trackdemon]

Usually run a few kms every day, play football weekly, so in moderate shape (I think!). Went to go for a run to clear my head, instantly hit a wall of pain as a very strong stitch developed right hand side below ribcage. What's that all about? Sleep & diet have been pretty poor recently but wouldn't have thought that would be connected. Seemed strange to get the stitch instantly as well, too painful to run through had to abandon tonights effort. Still a bit sore now tbh, could I be mistaking a muscular issue for a stitch?

[DervVW]

eating too close?
I've found eating close to a run can cause me to have a stitch