In reply to Dave B:
> Your shoes are possibly too narrow.
> Most cycling shoes are v narrow.
I tend to agree, except that I currently have a pair of Fizik shoes that tighten up well enough but are really quite wide, to the extent that I have to have the cleat all the way over to the inside to get enough clearance between the shoe and the crank - and it's really marginal if wearing neoprene overshoes. I've had Sidi, Decathlon and Mavic shoes in the past. Sidi were really narrow, ditto Decathlon. Mavic a bit more room. Sidi's died from an overwhelming stink. Decathlon donated for being uncomfortable (sounds similar to the OP's problem), Mavic sole snapped. Fizik likely to die of being nominally white but hanging on to every spot of road and chain gunge and looking disgusting!