Bearded dragons swollen belly

Question
Hiya im asking about my bearded dragons belly it feels like he's gona pop, i think im doing everything right im doing everything it said on this website he's 7 months old in a 3foot tank UVB bulb 6 inches above him basking temp between 95-105F and cool end high 70's, his substrate is calci-sand and we had been feeding him on hoppers because thats what the pet shop was feeding him but found out there only ment to be a treat and are now feeding him crickets, he loves carrot and apple but his belly has been swollen since we just introduced him to strawberries could this be anything to do with it? he poos about once a day but he does feel like he's about to pop or something.

Answer
Hello Melissa,

Do you have any pictures of him that you could post for me?  Also include a picture of the tank as well.  The tank size is great for him.  
What type & brand of UVB light are you using, a fluorescent tube bulb or a compact/coil light?
Are you using a bright white basking light or a colored light for his basking bulb?  Is the basking light directly beside his UVB light on one end of the tank?
The thermometer that you are using, is it a round stick on type, a digital probe or a temp gun?
The hoppers are fine as a staple, but, so are crickets.  If you feed both, then he will get a good variety of food along with greens & veggies.  
The best greens are mustard greens, collard greens, dandelion greens, endive, escarole, rocket, turnip greens & usually butternut squash or winter squash varieties work well as veggies.  You can feed carrot too, but make sure it is mixed with the greens.  
As far as fruits go, really they only need fruit a couple of times per week because of the sugar content.  The apple has a lot of fiber so if it is fed too often, it could cause diarrhea & so could the strawberries.
Unfortunately, the substrate you are using, which is calcisand is "calcium based" which is not safe.  It will clump up like cement when it gets wet, & it will be almost impossible to pass through, & if it does pass through is painful.  This substrate will cause terrible impactions in reptiles.  I would recommend taking the sand out & replacing it with non adhesive shelf liner, reptile carpet, tiles or paper towels for safer alternatives.
Are you giving any calcium supplementation?  If so, how often?  At his age, he does need calcium 5 times per week since he is growing rapidly right now.

Tracie