She may have something in it; a grass seed, a splinter, anything tiny that you can't see. Both of my girls had something in their paws (at different times). I only really noticed because they seemed to be paying a lot more attention to it by licking it a lot more than normal and eventually Thumper didn't like to put her front paw on the ground.
How long has your bunny been like it? It could be that if she does have something in it then it might come out on its own, but if she's quite sore with it (which it sounds like as she's not putting it on the floor) then you have no option but to take her to the vet.
Bear in mind that even when she is covered by insurance you would have to pay an excess fee, usually around £50, so you won't gain anything by making her wait for another 5 days as the bill will probably be less than that anyway (mine was), depending what's in her foot of course.
Personally as she's finding it difficult to put her foot on the floor you should take her to the vet.
Sorry; just realised that the bunny with the poorly foot is male, not female.
When you go to the vet, take them both. You won't be charged for taking them both but you really shouldn't separate them if you don't have to. I have never ever taken mine to the vet separately, even if it's only the one who needs to go.