Hello! My hedgehog, Atticus, is about 5 years old (he's an oldie!) and he hasn't had any health issues until now. He has a lump on the side of his body- appears internal (see attached photo). Was wondering if anyone had any idea what this could be? We took him to the vet and the vet said that he could give some antibiotics or knock him out and take a sample. We opted for the antibiotics to see if they would help and if not, we will bring him back for a sample.
His diet and behavior is pretty much the same- he is just a bit less active than before (it could be because he is old).
Link to photo: https://drive.google.com/file/d/1Yf_...ew?usp=sharing