I need help figuring this out!

My fiancé has had a bed wetting problem since he was little. It stopped for a couple years and out of nowhere it started again.. We've read that drinking coffee, alcohol, or milk before bed can help prevent it, but it doesn't help.. He won't wet the bed for weeks and then randomly start again. I know he has issues with holding it in during the day, and usually if he has to go he has to go, but I am really hoping there is something we can do ourselves! ( Especially since we definitely can't afford to have a specialist look at him.) if anyone knows anything please help!