Puppy stopped peeing in the same location

Question
Hi,
I hope you can help me.  Here's the thing.  We got our puppy when he was 7 weeks old.  We had a crate for him and almost immediately we were able to train him where to go to bathroom.  We were all set, he always left the house and went in the same spot.  We even got him at a point that when he was upstairs with us, he would go downstairs by himself and if the door to the yard was open he'd go outside.  We did not need to watch him or go with him.  We rarely had any accidents...if we did it was mostly our fault as we weren't careful.
Anyway, about 2 or 3 weeks ago, he stopped wanting to go pee.  He'd hold it till he can't hold it any longer even if it's in the house.  All of a sudden it's like he has forgot where to go?!  We bring him there but sometimes he just wants to sit down, so we have to wait - put him on a leash and constantly stand him up.  At times he doesn't even want to come out of his crate unless there's food involved - he just lays there even if the crate door is open and I'm calling him.  When we go for walks, he pees very often - almost too often.  But when we're at home he rarely pees.  He still goes #2 in the same place, but not #1.  I'm not sure if he's sick or just being stubborn for some reason.  Or got scared of something?!  I just don't know.  Any suggestion would be greatly appreciated.

Answer
The easy answer is take him to the vet.  If it is a physical problem, you can't train him out of it.  

If the vet finds nothing, make him keep walking on lease except to stop and sniff.  He will only be able to hold it so long.  After the vet visit, post back and maybe I can come up with more.