How much does he weigh?
Is he acting restless?
Did he get a bath recently or play alot in the snow?
When did you give the aspirin?
He weighs about 78 lbs
He just got up to eat some food and drank some water, but now he is laying on theground with a pillow spread out. When you ask if he is restless... he is sleeping so Im not too sure...
He did get a bath on monday and he always loves to play
I gave him a baby asprin around 0930 mountain time
He may be dealing with a mild strain or sprain. There is also a slight chance of a problem called swimmers tail or limber tail. The fact that a bath was given does make this possible. This is a neuropathy that can occur after swimming or a bath. Dogs present with the difficulty lifting their tail and they act a little sore in the rear. It typcally passes after a couple days. Now, this is unlikely, but I thought I would mention it. This is more likely a sprain or strain or minor intervertebral disc issue. You have alot of dosing room to work with. In about an hour, give a full 325 mg aspirin (or four baby aspirin -- 81 mg). You can give this twice daily. This should be enough to calm down any of these more minor issues. If the symptoms persist or they worsen, then I would look to having him seen.
I hope this helps and gives you direction.