If you've really put them through a year of intensive use, you
probably need new shoes, dude. Usually with squash shoes, the soles
remain functional longer that the shoe's support mechanism. Foot
problems develop when a shoe's support goes, like plantar fascia(sp?).
There's a chance that the problem could be the floor of the court
you're using which may have got slippery with the change of season.
But it's probably time to spring for a new pair of shoes.