Need advice for a sweet dog who turned aggressive.

So one of my clients has a golden-doodle that’s about 2 years old. I’ve been walking him for almost a year. Everything was smooth till summer hit and her kids got out of school. So it turned into her kids handing me the leash, but our walks were rough since they got home because he wants to stay with his pack instead of relieving himself. Now that the kids are back to school. It’s back to just him and me. Yesterday I came in and he seemed a little off, but he let me pet him. When I went to go get the leash, he got really aggressive and bit me a couple of times to the point I bled. I didn’t back down because I’m not going to let him dominate me, but I had to back down because I didn’t have permission to pin him down, and they got cameras. I don’t want them to think I’m abusing the pet. Today I went up to him and automatically started growling at me. Idk what to do, any advice is helpful.