Are you able to get access to these wherever you are?
http://www.kritterscrumble.com.au/
I went to the pet shop yesterday to get some more aspen, I initially used carefresh but switched to aspen for a while as I thought the paper bedding looked too dirty. I dont think it was too good with odor control either (I clean the cage every week, pick litterbox every day)
Aspen was OK, but yesterday the guy at the pet shop said that the dust from woodchip beddings are more microscopic than paper bedding dust, and that the wood dust builds up inside them while the rats can process paper dust.
I wasnt really keen on going back to carefresh so I decided to try the kritters crumble, which the store was using for their rats.
The guy said it was fine for their health, but he didnt really like it as the bits were small and got stuck to rats fur sometimes, making them appear a little dirty. My rats dont really roll around that much on the bottom level and I dont exactly have my rats for aethetic pleasure haha
Decided to try the kritters crumble, looks really nice in the cage and looks natural. The rats dont seem to mind it either, so far no smell and all good
So yeah you might want to try experimenting with different stuff to see if your rat allergic to aspen reacts to other stuff