Definitely try the food diary. There’s a possibility that you’ve developed a lactose intolerance, even if you were fine with dairy products in the past. Try cutting out the dairy products for a month and see if that has any effect.
Have you recently added any new things into your diet? Especially high fiber foods such as fruits and vegetables, or even a fiber supplement? When you try to add too much fiber into your system too quickly, like if you’ve been a big meat eater and you suddenly start eating more like a vegetarian, you can get a lot of gassy rumblings.
Beano is definitely worth a try, if you suspect that the gassiness is in fact coming from eating a lot more fiber containing foods, especially beans and the cruciferous veggies such as cabbage, cauliflower and broccoli.
You might also have acid reflux, which generally involves a lot of rumblings and burping and farting, but usually has some burning pain involved, usually right around where your esophagus is, way up near the heart (hence the term heartburn). Heartburn can be caused by eating too much spicy food and too much fatty foods (meat, cheese, fried foods in particular) and you are more likely to get heartburn if you eat a big meal late in the evening right before you go to bed. Laying down to go to bed, or to take a nap, shortly after you eat a large fatty meal is also likely to cause heartburn.