I suggest
bathing him more often if he's having trouble pooping to the point that he doesn't go for that long a period of time. The warm baths relax their muscles and stimulate them to go....
I'd make sure your UVB lighting and temps inside his enclosure are okay as well, because something I've found with my new rescue male, Mix, who has severe MBD, is that he pretty much only is able to go in a
bath, as it seems he doesn't have the strength in that area to go unless he's in warm water. I've had him almost 4 months now, but when I got him he was 8 months old and severely impacted, which caused partial paralysis in his back legs, and even after we got that cleared up he still could rarely go if not in warm water because of the MBD and the weakness in his back end. So I make sure to put him in a warm tub once a day and he immediately poops when he hits the water, then I clean him off and get him out. I'm not saying that there is anything wrong with your beardie, just suggesting you make sure, as I wasn't really aware of this kind of "constipation" or "inability to poop" due to MBD and related muscle weakness until I rescued Nix. He's not at all impacted, he just can't push it out...