Keeper goes out on loan
The 19-year-old has yet to make his first-team debut for the League Two side although he has been an unused substitute on seven occasions.
Dons boss Martin Allen allowed Webb to join Thurrock on loan earlier this season.
The keeper was an unused substitute for Justin Edinburgh's Fisher side on Saturday in the 2-2 draw at Braintree. He is expected to replace the suspended Paul Nicholls for next weekend's clash with Thurrock.