4 year old suddenly urinating inappropriatlely

My 4 1/2 year old has suddenly begun peeing on the carpet.  I questioned him about it at first when I began noticing the wet spots, he denied doing it.  I thought it could have been one of our cats until the other morning I woke up and he was urinating on the carpet outside our bedroom door, which is also right outside the hall bathroom.  

We spoke to him about it and said that he would not do it again.  Later that evening he urinated again in front of the laundry area right outside his bedroom door.  I took away his TV and other favorite things.  Spoke to him again this morning and he said he would not do it again.  Went out of his way to tell me that he used the potty each time and gave me a big hug.  I told him I was proud of him.  

I had been cooking in the kitchen when I walked into the living room to check on him when I walk over a wet spot.  Sure enough he had urinated again.  Asked him why and he said because the toilet is broken.  

We are renting a house and have been here since May.  The toilets are difficult to flush and he is unable to do it, but it has never been a problem until now.  Why all the sudden would he begin urinating on the floor?  I will have my husband buy new hardware for the toilets so that hopefully my son will be able to flush the toilet.  Just need to know why this began so acutely?