Why is the potty training regressing instead of improving ?

I started potty training my son 5 days ago. He is 2 1/2 yrs old. Within 3 days he had sussed that he needed to ask fo a wee wee and he used the potty brilliantly he has yet to do a poo on the potty. So we have had great success for 2 days, each time he gets a sticker and a chocolate on, much to his delight ! Today is no different in routine except he has weed himself everywhere ! When i explain to him that he has wet himself he then tells me he should have used the potty, but then subsequently wees himself again ! Each time he has done a poo today i have said "Where should you have done it? and he says " In the potty". He just weed all over the carpet and called me in and said " Look mommy" ! I don't understand how we can go from a child who only yesterday was telling me he needed a wee to this ! He hasny used the potty successfully today at all ! Can anyone help ! Is this normal behaviour and do I need to chill out !