Sorry this is long, I just want to get all of the details in...
I'm not sure where this has come from, but Cooper all of a sudden has what seems like an irrational fear of our backyard. He'll be 2 at the end of this month and every day since he was 16 weeks old, I've let him out the back door to go in the yard at least 4 times a day. He goes down the back stairs, goes to the bathroom and then comes back up to the door when he is ready to come in. The last 2 or 3 days, he seems terrified to go in the backyard. Even when I just open the back door, he'll run back into the house and I'll have to go grab him and then pretty much push him out the door to go outside. The last 2 nights, he wouldn't leave the back door before bed until I put on shoes and took his collar and pulled him down the stairs and into the yard. Last night I had to hold his collar the whole time we were outside until he peed because every time I let him go he ran back up on to the stairs and I didn't want to let him in for the night without going. Then this morning, I let him out and he actually went down the stairs on his own. I let him in about 10 minutes later and went back upstairs to get ready for work. When I came back down about 20 minutes later, Cooper had pooped and thrown up on the carpet in the living room. I just cleaned it up and put him in his crate for the day in case he got sick again during the day. I came home on my lunch and let him out- no more vomit and he hadn't gone to the bathroom. He peed again in the yard, but I had to go out with him and he ran back to the stairs as soon as he peed. He hadn't eaten his breakfast so I figured he didn't have to poop again. I got back from work around 7 and let him out of his crate again in to the yard. I walked out there with him and he peed and ran back to the door. My roommate was just in the kitchen doing dishes and he pooped on the kitchen floor right next to her! He didn't give us any indication that he needed to go out again. He has never gone to the bathroom in the house (except when he was sick and had diarrhea) since he was probably 20 weeks old. I have no idea what could have caused him to have this sudden fear of the backyard and don't know what to do to get him over it.