(I am not a physio, but) I have experienced this pain for years. When younger it was particularly hard hockey pitches that would set it off.
These days, because of a lack of exercise means I’m a buffet, I find brisk walking does it. Worst is straight off the (2 hour) train journey to London on Monday mornings – sit stationary and then blast down the platform and along the street to the tube. Am usually crippled by then.
I don’t believe it’s shin splints in my case – the pain isn’t associated with the shin bone. Instead, I think it’s a short term case if compartment syndrome in the muscle st the front of the shin (anterior tibialis), which is down to the muscle expanding with blood flow as I suddenly demand it walk briskly before the less flexible tissue surrounding the muscle has had a chance to relax.
Slowing down helps. Also, some pre-walking exercises can help: heels on floor and raise foot upwards 20 times, repeated 3 times. Also try kneeling with your feet pointing behind you and sit back on your feet. Last exercise is stretching calves – when I did some yoga this seemed to help.