So I went and killed the stag to talk to Hircine. Then, when I went to the grotto Sinding wasn't there, he was on the road to Whiterun from Riverwood. I went to where he was but before I got there I was turned to a werewolf by the ring. I decided I'd keep going because I should've reverted by the time I got to him. I didn't and when I got to him he started running off towards the grotto.
When I got there after him and went inside, I didn't get the conversation with him on the rock. I managed to catch him before he killed all the hunters and agreed to help him. After we killed them, he started attacking me. No matter what I tried it wouldn't let me talk to him. I think me being a werewolf when I met him outside bugged the quest. I ended up killing him and got the hide from Hircine. I was wanting to get the ring but I didn't know what else I could try and I had no save to go back to before I met him because I'm really bad at saving frequently, I usually rely on autosave unless it's at an important part I don't want to mess up.
Does anyone know of if there was a way to calm him down and talk to him? It doesn't really help me now but if it ever happens again I'd like to know what I can do.