From what I have read, aspirin can be given to rabbits, but only after you have consulted a rabbit savvy vet.
Here is one link regarding aspirin for rabbits, which does say it is safe, and gives the dosages, but one of the comments from a member of Bunspace posted that her vet said aspirin is dangerous.
http://www.bunspace.com/groups/topic?tid=3814&posts_tgp_no=last
Here is an older thread on BB regarding aspirin: https://binkybunny.com/FORUM/tabid/54/aft/61598/Default.aspx
I looked at a few different sites. Some say aspirin is okay to give, as long as your vet okays it, but other sites talk about the dangers of aspirin.
Besides the emergency clinic, are there any other vets nearby that might see your rabbit? Even vets that mainly see dogs and cats and don’t see a lot of rabbits, could x-ray or examine the foot and hopefully get your bunny some help if needed. You could either call your regular vet back and ask the vet’s opinion on aspirin, or try calling some other vets that are close to you, who have treated rabbits, and see if one could see your bunny today or tomorrow.
I hope that it’s nothing serious and he is better soon.