Help! My 2.5 year old will not sleep at night

my son has been sleeping in his own bed for almost a year now no problem. he has been potty trained for about 6 months and would usually get up around 2 am and 7 am and me or his dad would help him go potty and get back in bed and go right back to sleep. the past week when he wakes up for his 2 am pee he will not go back to sleep. we've tried rocking him, laying next him until he's a sleep, being consistent to lay him back down, we've tried a stern approach, a gentle approach and nothing works. as soon as we leave the room he's right back up. this goes on until about 7 am usually and we give in and sleep on the floor of his room. its become painful mentally and physically and we just don't know what we can do. I feel so bad for my fiance because he has to get up at 6 am for work everyday but he still insists on taking turns or doing it as a team. anyways if anyone has any ideas other then let him sleep with us or sleeping on his hard cold floor that would be awesome.