One of my triplet boys was staying dry at night for over a month with no accidents and he suddenly started wetting again and very heavy. I took him in to see if he may have had an infection and he did not. The doc said that it is just him, kids revert sometimes and nothing you can really do until the bladder is really fully mature.
I stopped giving drinks after dinner. Dinner was the last drink of the night. I did a double void before bed. half hour before bed and again right before crawling in. I used Pull Ups because that brand ran a bit bigger for my bigger boy, who was also 3, and it had velcro sides in case he had a heavy morning or an accidental poop so it was less mess to take off. I never used Goodnights for any of my kids. They cost more and got less. If your son can still fit into Pull Ups use those. You'll get more for your money.
**I wanted to add that you should use waterproof mattress pads that are fitted underneath the sheets so it does not ruin the mattress. I always used these with my 5 kids from birth forever. Kids as they get older will take foods and drinks in their room or even water and will spill and eat in there even when they know they're not suppose to. Even when they got sick and threw up during the night, it always protected mattresses.
K. B
mom to 5 including triplets