Red Bump on Dogs Side?

Hello,

I have a 6 year old female Australian Shepherd. about a week ago I noticed a small red bump (3rd picture). Since then it appears to have grown slightly (1st and 2nd picture). She's acting normally, she's not itching it, and it's not painful.

Anyone have any idea what this might be? I'm thinking a vet visit might be in order...

https://imgur.com/a/EhwFZTg

Thank you all in advance, I added a normal picture of the girl at the end lol.