One of my regular visitors of fox squirrels (I call her Momma Squirrel) who I've known for four years now, has an injury on her back. A week or two ago I noticed a small section of fur missing on her back, but couldn't make out if the injury was deeper. I figure maybe from an altercation with rival squirrel or predator. But now, some of that fur has regrown, and now has a noticeable bump on her back. It is not just some fur out of place or sticking out. It is a 'hard' lump. Maybe about an inch in diameter and 3/8" high. I'm very concerned, but realize there is probably nothing I can do like bring her to a vet because she is 'wild'. My guess this tumor like bump maybe a possible infection from that injury. I will try to upload this photo image, and maybe some of you professional rehabbers can tell me what this is. Any advice or what possible things in the future will certainly be appreciated.