monitor has gas?

[dinosaurdammit]

So the past few days pajaaamas has been getting bloated and every time he passes stool he has a huge go at a fart. Its loud its long and I know he feels better, whats causing him to get so bloated with gas?

his diet for the past few days:
weaner rats
craw fish
squid
quail chicks/eggs

which food would be causing the gas? The eggs? I have no clue but he looks miserable. Sometimes he gets so bloated he just looks like someone pumped him full of air and he just looks at me all sad like because hes too bloated at times to get in a burrow. Just has that longing look. After he goes to the bathroom he is totally back to normal. Is there something I can change him to to decrease the gas until i either figure it out or he quits having the problem? He refuses crickets, mealworms and night crawlers now- he goes through rejection phases where he wont eat something but then he will after some random amount of time.

can a lizard be allergic to a food kinda like people can be lactose intolerant? Its the closest relation I can make, its like he has eaten something that just doesnt set and bloats up like a hot air balloon, at this point I have NO clue which food causes it because he pretty much eats 2 or 3 different things at a time.