If she will not put any weight on the foot it could be a snapped nail or a cracked nail is hurting her when she puts it down, it might be a bad sprain or it could be a break.
You can check the nails by touching each one by one to see if any make her react (watch for biting as a nail with the quick exposed is really painful).
But if that isn't it and she isn't touching the ground with the foot willingly then I'd see your vet as an x-ray and possibly a splint or some pain meds could be what she needs.
You can try a cold damp facecloth around the sore area to reduce pain and inflammation but overall a good anti inflammatory pain med from the vet (over the counter ones are pretty much not safe for dogs) or even a splint etc. could be a better choice for her comfort.
Hope this helps you!
You can see if she is better after a rest but if your vet is hard to book with you might make an appointment for later and cancel it if you decide you don't need it.
You can wait overnight too and try a cold compress to see how she does.
But a bad sprain or a break or a broken nail (common with a twist situation) may need vet attention or pain meds.
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