I am a DSer 3 years out. Carbs do the gas and foul smell for me. So bread, rice, potatoes, Beans, sugar, chips - I will get gas that sounds like a herd of buffalo are coming through. Everyone is different. Some people get wicked diarrhea from certain foods. I did not have any food issues (lucky I guess). Dairy can do it, carbs definitely do it, and certain chemicals can do it. Curb your carbs and see if the gas doesn't die down.
Smelly BMs - part of that is the food you eat. If you stay close to clean Protein, protein powders, a little veggies, a lot of clean fat (you need to eat 5 times the fat as a normal person), your smell and gas will subside. By clean, I mean eat from the perimeter of your grocery store – your food should not be coming out of a box.
If it doesn't get better, get a script from your doctor for an antibiotic to knock down some of the colon bacteria (and definitely stop eating carbs because that is what is feeding the colon bacteria).
Even when you eat cleanly, you will have smelling BMs. Half of what you eat isn’t getting digested. It is sitting in your guts at 100 degrees in a Soup of bacteria all the way through your intestines for 24-72 hours. So you are releasing fermented, bacteria soaked undigested food at the other end.
I’ve used all the poo products and the one I use at work is called Ozone Spray. It’s the only thing I’ve seen that will kill the odor on contact. It will also suck the oxygen out of your lungs, so spray it and get out. Also keep flushing. Don’t let it sit in the bowl cause it will waft up and start sticking to the walls and mirror (kidding here, but it will start traveling down the hallway and kill small children and pets). My family is disgusted by my bathroom smells, and it will stay in the hallway and bathroom for hours – so keep flushing it down.
It gets better as time goes on. At the 2 yr point, your body will adjust and your bathroom issues will level out.