puppy lab bowel movement cycle

Question
I am a new puppy owner.  My lab puppy is 12 weeks and was doing quite well with regard to being housebroken and potty trained through the night. Yesterday, we decided to take him swimming and we think this was a mistake because he eliminated in his kennel (I bought a kennel instead of a crate by mistake) at 2am (possibly the excitement of swimming and drinking some of the pool water?).  My husband was cleaning the kennel and I was bathing him in the wee hours of the morning.  This has happened on one other occasion when we had friends over and we think the kids fed the puppy too many treats.  Anyhow, tonight as I was about to go to sleep, I decided to take him out one more time at about 1:30am.  He had a bowel movement and now I'm totally confused because that's 2 consecutive nights that he has eliminated at around 2am.  How do I change this cycle?  I cannot keep this up (cleaning and bathing him at 2am).  I need your advice.  Thanks.  If you're wondering about food intake, I feed him Nutro Natural Choice Puppy Food for large breeds and I feed him 1.5 cups in the morning and evening and 1 cup in the middle of the day.  Is this too much?  I think he weighs about 22 lbs.  The veterinarian told me I should feed him as much as he'll eat.  "You can't overfeed a puppy."  Thanks for your time.

Answer
Find a new vet.  Overfeeding a young Lab is one of the worst things you can do for its joints.  There was an extensive discussion of weight in a recent newsletter from a service dog school.

''Obesity is the number one nutritional disease affecting dogs. It's estimated that 25-45% of dogs in the US are obese. Studies have shown that joint and locomotive problems increase by 57%, circulatory problems by 74%, respiratory problems by 52%, skin problems by 40% and cancer by 50% in animals that are overweight.

Large breed dogs that are overweight also are more prone to developing hip dysplasia. Obesity is especially dangerous for young puppies, as their underdeveloped frame cannot support the extra poundage that it must carry.''

Likely much of the above draws on a study Purina completed a few year ago.  You can find more on it starting with this link, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx  Although anything on feeding dogs coming from a dog chow company is suspect, the study was published in the JAVMA.  

I have an 11 week Lab I am feeding 0.8 cups each of 3 times a day.  My vet was very pleased with her condition last Wednesday.  So was a volunteer trained to monitor the health of puppies being raised for a large dog guide school.  By keeping their puppies lean, and switching to adult chow at 4 months, they have almost eliminated hip dysplasia in their thousands of Labs.  While you are lucky to get a Shepherd to eat enough to hide its ribs, Labs, and their Golden cousins need to be carefully regulated.  

I am hoping the problems of the middle of the night bowel movements are a temporary thing due to disrupting his schedule and ingesting things he shouldn't.  Be sure and exercise him before bed time.  This is a tactic I use frequently before taking a puppy in public places.  I give them a good walk outside in the parking lot to make sure any bowel movements take place there, rather than after I take them inside.