Unknown sickness

Question
My dog, Chubby, a Maltese was on walk at about 10. I noticed he was struggling to get home so I tried to pick him up. He immediately yelped and just sat there. Quickly I brought him home and he wouldn't eat or drink. He simply lay down on the cold tile panting continuously. When he got up (about 2 hours) he wouldn't eat or drink and was shaking but now unable to lay down. What is wrong?

Answer
WHY would you post a question to the internet, which could be answered in anywhere from one to three days, when you could have called the veterinarian or gone to the emergency veterinary clinic????

Your dog appears to be suffering and in pain.  HE NEEDS TO SEE A VETERINARIAN ASAP.