Okay, so before anyone mentions it, this just started yesterday. I was sleeping and a knock at the door had her getting up quickly and running to see who it was. After all was settled when she walked back over, she was crying. Now today is Sunday and this happened late last night so that is the only reason she hasn't been to the vet. I will definitely make sure she gets there tomorrow morning when the vet opens for the week. Now at first I thought it was a hurt paw, but then I watched her and saw that she wasn't limping. Once she's up, she's walking fine just tentatively and not running everywhere like she usually does. She is using the restroom without pain, I've been watching that too. She's in heat so I also thought okay it's just an infection causing her pain in her backend, but there is no discharge other than the normal blood and like I said she is using the restroom without pain—also she is not drinking excessively or avoiding food like she would if it was an infection. She just is in pain, like crying out loud pain, when she tries to get up from laying down. Also she always sleeps on her side but last night she slept on her stomach only. And I watched her and around 3 am in her sleep she tried to roll over and promptly screamed and laid back on her stomach. So, yes she is going to the vet tomorrow morning, but I just want anyone's opinions on what this could be. I'm definitely believing it's a back issue, maybe a ruptured disk? I would appreciate your thoughts.