Why is my child purpously weeing on the floor?

[ChloeOsborne95]

My son is 3 next month and has recently been toilet trainined. It has taken about a month and a half for him to grasp the concept of toilet training and up until 2 days ago was doing extremely well, better than I had imagined and was more than happy to take himself off for a wee/poo on the toilet. He would tell me ‘potty upstairs’ when he needed to go or would just run off and go himself. He has had no actual ‘accidents’ when out and about or in the house, up until 2 days ago. It started with him standing up, saying potty and poo and refusing to use the toilet and telling me no. He is not very vocal so this is often the most I can get from him regarding the toilet. The next thing I know he has wee’d and poo’d on the floor whilst standing up and then said ‘oh no’ despite doing this purpously. I think the mistake I made was telling him off and giving him a time out because since then he will purpously wee on the floor. He even climbed onto my bed yesterday afternoon and stood up and urinated on my mattress. I don’t quite understand why he is doing this? He has also been doing very well staying dry throughout the night for the past 2 weeks up until 2 days ago also where he has wee’d the bed both nights. This I expect as i know it is the hardest part of training and I use a washable waterproof mattress cover, as I’m trying to make him understand when he wees during the night he will be wet and needs to wake up for the toilet or there is the option of a potty in his room which he has done really well with up until now. He has done so so well, and I’m not expecting perfection or him to be completely dry straight away and I know there may be accidents and bed wetting which is expected. I just don’t quite understand why he is doing his business on the floor several times over the last 2 days.

Any advise would be great.
Thank you in advance.