Hi, I am Dr. Peter and would like to help.
1- Is he making the attempt to urinate or just has not attempted to urinate?
He is attempting as we speak. He has taken more water and is pushing quite hard I stop him from doing this when I think he is trying to hard. I have let him out several times today; I cannot walk him far as he still has a leg injury. He attempts to pee constantly when he is out.
He has just come back in and taken more water, the door is open but he has opted to lay down indoors.
This is most likely related to having bladder stones; a stone may be blocking the urine outflow and this is why he keeps trying to go unsuccessfully. This is an emergency and he needs to be seen by a veterinarian today. This can not wait until Tuesday. His bladder could rupture or suffer irreversible damage. I would strongly recommend you take him to ER vet. In the meantime, take the water away so he does not continue making more urine.
If you have additional questions I will be glad to answer them.