If you are concerned about your helmet then seriously consider replacing it. If it is old, the pads are probably getting ratty, the shell is scratched etc. Go to a bike shop and try on a few helmets, I think you will find the newer ones are a lot more comfortable. Essentially the more you spend the more ventilation you get, and perhaps the less it feels like you are wearing one.
Remember, no matter the price they must meet Australian Standards. You can make your own mind up if this standard is sufficient