I took him to the vet this morning to have him looked at. They told me that tumors in cats are not very common, and it's hard to tell where the tumor ends, since it's so attached to his arm.
His best bet would be to amputate his arm.
For now, the vet gave me some antibiotics, to keep the open wound from becoming more infected. But the sooner I can bring him back to have his bad arm removed, the better it will be for him.
I love my Hellie the most in the whole world.
He's been with me since he was born. He'll be 10 years old in September of this year, but still has a lot of life left in him.
Any help that you can offer will go directly to removing my dear Hellie's tumor arm.
I'd be so grateful for any help, no matter how small.
Thank you so much for reading. I'll update as soon as I have more information.