Hi! About 3 weeks ago my dog had a tick on him that has likely been on him for a few days. I'm not sure if we didn't get the head out or what, but I'm wondering if he needs a trip to the vet because it's a hard lump that wont go away now. It's not red and doesn't bother him at all so I read online to "just let nature take its course"? Thanks in advance for any help.