Brief Answer:
Disturbed gut flora.

Detailed Answer:

Hello,

Have gone through your details and i appreciate your concerns.

Malabsorption is also a common cause of foul-smelling poop or gas and improper digestion is cause of foul smell in vomit.
Malabsorption occurs when your body is unable to absorb the proper amount of nutrients from the food you eat. This generally occurs when there's an infection or disease that prevents your intestines from absorbing nutrients from your food smelling can also be caused by a change in your regular diet.
In our gut there is a balance between good and bad bacterias.When this balance is disturbed food starts to ferment inside causing production of toxic gases like hydrogen sulphide methane etc which give foul smell to fart and vomit.
Suggestions-
Ensure that raw foods are cooked properly before you eat them. This includes beef, pork and eggs. Also, a good practice would be to steam meat before actually cooking it.
Stay hydrated by drinking up to eight glasses of water a day, as it will help the absorption process and prevent constipation
Consume probiotic like VSL#3 twice daily this will replete your depleted gut flora hence restoring digestion.
Include Probiotic rich food like yogurt or supplements that help combat invasive bacteria in the gastrointestinal tract.
Eat fruits and vegetables. The added fiber will help cleanse the colon.
Tests suggested-
Stool test to rule out infection.

Thanks!

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