I don't know what's wrong with my cat. This is his shoulder there's something coming out of it https://www.youtube.com/shorts/hLaIcSrgkjU

I took him to the veterinarian in February for a lump on his shoulder, at the time it was the size of an almond. Its been growing and it was the size of a golfball and then stopped growing. So I went back in April and they did a needle test and told me it wasn't cancer and he was fine. okay so its now and monthls after that and this morning his shoulder did this. He sleeps on pillows, doesn't jump on counter the highest is the couch. I'm very careful with him. I don't understand how this could happen or what's wrong with him.