It's like housebreaking a puppy!

OK, I'm hoping for some really great insight or advice here.... Tanner has been potty trained for the past couple of months and recently, he's even started wearing undies to bed with no accidents. He's never had an accident in his pants during the day and it's been several weeks now that he's dry at night as well. Here I am thinking "Way to go little buddy!" Except, he's now having a completely unexpected and mind boggling set back..... Several times now (at least 8) I have found a puddle on my carpet! Yes, you guessed it....he's peeing on my carpet! UGH! It started out upstairs, he did that a couple of times, peed on his brothers belongings a handful of times (you can't imagine the uproar that caused) and then it moved downstairs. In the past week, he's taken to walking into my bedroom and letting it flow right there in my doorway! He's done this 2-3 times and yesterday, brother Jon caught him peeing in his own room! (He shares with Jon) I sent him to bed early and of course he was really upset. EVERY time this happens I talk to him about how naughty it is and how he needs to use the bathroom and the bathroom ONLY! Well, this morning, Jared calls me into Tanner's bedroom just in time to see him pulling his pants up and of course....there's a huge puddle on the floor. Well, not so much a puddle since it was quidkly soaking into his carpet! Our household has been pretty chaotic lately with his brothers and their attitudes. We have a pre teen, a bipolar on meds and an I'm pretty sure he's bipolar on no meds. SO, needless to say, there's a lot of arguing going on. I think maybe this is his way of acting out to say that he is not liking the household dynamics right now. Any other thoughts or ideas? I need to know what to do to stop this and I'm stumped! I've never had this issue come up before. Needless to say, he didn't get to go on his pumpkin patch field trip today with his class! If you have ANY advice, ideas, comments, I"d love to hear them!