Knot on cows back

[swfa farmer]

hi I am new here, anyways i was checking the herd today and I noticed this knot on one of my cows spine. She is in pretty good condition and walks and eats normal. The other day I noticed she was in heat so this knot may be from the bull. Like I said she doesn't seem to be in pain or anything but it doesn't look right. What could this be from?
Thanks

 

[dun]

Turned

 

[JMJ Farms]

Bulls front foot caused bruise? Horsefly? We have some horseflies big enough to possibly leave a knot that big. Or she may have went under a limb or something else and bruised it?

Best I can do. Maybe someone with a better eye will answer shortly.

 

[dun]

On older cows I've frequently seen the spine have weird bumps like that. Just had to do with age and didn;t bother them as much as it bothered me seeing them like that