Yes I am a numpty... she was in her car seat strapped on top on the supermarket trolley on the special platform thing - that helpfully is at the right height to ensure I cannot see where I am going... anyway I ran the trolley full tilt into a bollard causing the car seat to tip and her head to jolt forward.
... Have I caused her shaken baby syndrome or bleeding on the brain or some other thing? - This happened before lunch and I can't stop worrying about it...
... she has fed well since, but slept more than usual... - during which I couldn't catch up on sleep for worrying! (only got 4 hours last night...)