Help!!! Is my dogs foot broken?

[SamanthaLittle]

I just noticed my dog is limping but i'm not sure if i should take him to the vet. he has limped before and it got better over time but it looks bad this time. theres a bump on top of his paw kinda towards [his] left side. He completly straightenes his leg out when he walks and doesn't want to get up. both our dogs have been wandering out lately and i think he may have gotten hurt. I have to know by tomorrow if i need to take him to the vet cause i work there once a week on wednesdays and need to call it in if i'm bringing him.

He's an Aussie

Please help. Thanks