We have a 17 week old chocolate lab boy. Ever since we brought him home at 10 weeks he has pretty much went outside. We even taught him to ring a bell to let us know when he has to go. He was doing great only about 3 to 4 accident a day. Two days ago he started just going in the house all time even when we have just had him outside he will come in and go right away. We are baffled he was doing so well.

Though it's not as common in young puppies, I would get him checked for a urinary tract infection.

A puppy should be taken out immediately after each meal since a full stomach puts pressure on the colon and bladder. Even though he has been ringing his bell, you should still take out after every meal and after excersise, after drinking etc.
Dogs do not think the way humans do. When you are unhappy with your dog, it assumes that whatever it is doing at the exact moment you show disapproval - is the thing that is upsetting you. For example:

If your puppy relieves himself on your floor and you show your disapproval five minutes after he has committed the act, the puppy will think that the mess on the floor is bad. He will not relate to the fact that it was the act of relieving himself on your floor that you disapprove of. The dog will eliminate, see the mess and get worried; you are now going to be unhappy. This is the reason so many dogs will relieve themselves in inappropriate places and look really guilty about it, yet they continue to do it. Dogs want to please, right?

Do yo crate while you are away?

I don't think this is an issue for a vet. Sometimes during house training puppies will forget. Just continue to stick to you routine. Continue to take puppy out after every meal, nap and playtime. I've house trained a lot of puppies and like I said, sometimes they forget. Its not uncommon for puppies to forget and make mistakes. You have a good routine down... just stick to it. When puppy makes a mistake, try to correct it by interrupting the puppy and immediately take the pup outside. You may need to stay out with the pup to make sure the puppy finished. During house training, I never allow the pup to watch me clean up the mistake. Mama dog cleans up after her pups while in the den... its time to grow up

Hope this helps

I would still take a urine sample in to the vet. Better safe than sorry.

Thank you for all the input. We do have a vet appt. on tues. so I am going to bring a stool and urine sample just to make sure everything is OK. Yesterday was a bit better I also spoke with a pet trainer from petsmart. Clarence will be starting obedience class next week and I will be going to a potty training class on sat. My floors are all tile and I had a rug in the living room that I pulled up in case his scent was still in there and washed the floors reallly good. Now I am putting him on his leash and taking him to where he was going outside and telling him to go potty. He did about half outside yesterday and when he did we praised him and gave him a treat.