dahlia
I became sensitive to onions in my late 60's, leading to a build-up of wind until I realised what was causing my problem. Many people become sensitive to different foods as they grow older - could you try eliminating one particular food for a week and seeing if things improve, and if not, try a different food? I also take probiotics daily, which do help. Good luck - it's no fun!
I experienced the same thing as dahlia with onions, but found that it actually helped to pay extra for organic onions.
I had too to be careful with other vegetables that are likely to cause wind, such as cabbage and beans.
I say "had" because the problem with wind seems now to have been part of having an over-active thyriod - now after a year and a half on medication and a normal thyriod activity again, I am not passing wind nearly as much, or passing such smelly wind either.
Perhaps you should have a word with your GP. I think we are all inclined to believe that a thing like this is just part of ageing, but my experience shows that there might just be a health issue that can and should be treated.