Possible Nipple Problem

I think this lines up with where her nipple would be, she has had 2 litters and is now fixed. I’m 99% sure this is not a tick but I could be wrong, I haven’t heard of them going under the skin.

Hello - I'm afraid it's hard to tell what this is from here.  You'd probably identify a tick - they're attached at one side / edge of the brown lump only, where the head is;  you can usually slide a peice of paper under the body and they get slowly bigger until they fall off.  This could also be a keratinous tag or accumulation of some kind (the stuff hair and nails are made of) / a cyst / the the contents of a sweat-gland sort of solidified with a reaction around it.  I wouldn't be surprised if that were the case.  However, it could also be any other inflammatory lump and I can't confidently exclude a melanoma or other skin cancer from here.  All lumps should be checked by your vet who may, if they can't prove otherwise when they examine it, ask to take a sample.  Please will you come back and let us know?

Ps sometimes nipples do change colour and if that is the case / they can't see a reason for it, your vet may also ask to take a sample.