What happend to my pet?

Well I bought m dwarf bunny on sunday and today is Thursday evening it was as big as my palm it was white with grey and it was fine today but then after 2 in it's sleep it was kicking and peed ounce so at 3:40 I noticed it was asleep still so I got it out of it's cage and it was breathing but it wasn't moving it was just hanging in my hand and I was worried I didn't know what to do and so I put it on my lap and it looked as if it was having a stroke then I waited till it stopped I put back in it's cage and it was opening it's mouth it was still breathing but it felt like it had no life in it until it just stopped and it had passed till now I can't stop crying I don't know what happened to it can you tell me me and my fianc� just barred it please tell me what had happened to my beloved dwarf bunny :( ���