Why does the smell of sulfury flatus give me headaches?

[electricvolcano]

I didn't always have this issue, but for sometime when my flatus has a strong sulphur odor, my head fills with pain as soon as I inhale it. It is just weird. The smell is already unpleasant, but I don't get the headache part. It is not the releasing of it, but the actual smelling or inhaling of it. I'm guessing that it either has something to do with hydrogen sulphide rich flatus as that gas is poisonous at high level, or it is just a psychological reaction. I won't know if the intestines could actually produce poisonous or harmful concentrations of hydrogen sulphide, or if headache is a reaction of hydrogen sulphide exposure. Is they any thoughts why I have this issue or how to remedy the odor? I'm aware of activated carbon tablets, but they are not cheap (unless you have info on a good supplier).