puppy poopy problem

Question
I have a golden retriever who is 12 weeks old.  We brought him home about 3 weeks ago.  His housetraining was going fairly well until recently.  He has been crated and was doing well at night until last week.  I started giving him some treats that, I think, upset his stomach.  He started eating a lot of grass and had several accidents in his crate at night.  The crate is a smaller plastic one and, needless to say, he was wearing his poop in the morning.  These nighttime accidents happened 3 days in a row.  I stopped giving those treats and he's not eating the grass anymore.  But he's still having accidents at night.  He messed his crate (and himself) again 2 days ago.  Last night I moved him to the basement bathroom, since he likes to sleep on the shower floor anyway during the day.  Last night, he pooped on the floor in the bathroom as well.  What can I do to stop this?  I take him outside right before putting him in at 10:30 pm and take him out at 6:00 am.  It seems to be getting worse.  I have 3 children under 5 and I have enough mess to clean up with them.  Any suggestions?

Answer
Is he still having lose stools?  You have to clear that up before the problem will go away.  Some dogs just don't tolerate changes in their diet at all.  It is best to stick to their regular kibble and little else.  I don't use treats much, and often as not, I just use a little of its regular kibble.  

If his digestive system hasn't settled down, try this for a few days:

OK, out of the manual I have from a large, knowledgeable dog guide school.  

Bland recovery diet for dogs.

3 parts cooked rice, one part boiled hamburger or chicken, or cottage cheese. I think you can substitute boiled potatoes for the rice.  Once in an emergency, we bought a plain baked potato from Wendy's.  

This is meant for short time settling a dog's digestive tract.  It is not the complete and balanced they need long term.  Once his stool firms, gradually go back to his regular diet.  

A rack in the crate reduces the mess from accidents.  They are available with the crates, but a piece of closely spaced wire closet shelving from a home supply place is cheaper.  For a golden, you may need to block it up 3-4'' above the floor.  Even with his digestive system back to normal, with some 12 week olds, there may still be accidents once in a while.