For those moms who suggest you quit being lazy and 'train' your children; they have obviously been blessed with kids who don't struggle with wetting the bed, that's wonderful for them, please try not to trip when you get off your high horse. Many, many, many, many studies have shown bedwetting is common up until age 10, and lots of doctors don't consider it a medical issue until as late as 14 or 15. My 9 yo wets the bed, always has. My 7 yo doesn't, never has. It's obviously not my lack of parenting/potty training skills that's causing the bedwetting or they would both be wetting the bed. Last night at practice one of the other moms (a nurse practitioner at a pediatric urology practice who treats mostly bedwetters) suggested to me that we check to see if he's constipated because constipation is the number one cause of bedwetting - the bowels push on and desensitize the bladder so the child can't hold it as long and doesn't recognize the 'urge'. You might consider having your 7 yo xrayed to see if he is constipated and then putting him on Miralax; the RN I talked to sees success in a large number of her bedwetters simply by putting them on a regular dose of Miralax & limiting liquid (and only giving milk/water period) after 6:30.
In the meantime they sell waterproof mattress overlays on Amazon or the bedwetting store. These go on top of the sheet so you just have to wash them in the morning. Good luck, and don't let the know it alls who don't really know much discourage you or make you feel bad.