Whats wrong with my dog?

I have a chihuahua and today I let him out one last time at night. I thought he was done pooping/peeing but when I got inside 10 minutes later, he pooped on my carpet I was so mad so I yelled at him and chased him around the house, first he hid under the bed then I used this cooing voice and he came out but then ran under the couch, he yelped though. He stayed under the couch for more than 5 minutes, I looked under the couch and just saw him lying there, and asked him to come out but he refused to. I tried to lure him with a treat and he still didnt come out, when I put my hand under the couch and try to touch him he would turn his head away and let out a yelp. Finally I let out my other chihuahua, and fed him the treat then my dog (under the couch) really got tempted and ran out of his hidin. He's acting normal now, but after he got out I brushed his hair and then he let out a yelp, as if he's afraid after a few more strokes he just acted normal again. I know its my fault for yelling at him and chasing him but can someone explain his behavior? What is he feeling and thinking and what about the yelps? I will never do this again because I had to practically beg him to come out.