Smelling odors thats arent there?

for the past few months , every time I get a headache or get really stressed out , I start to smell things that arent there , like rotten food , wet ashes ( fireplace etc ) if my headaches are really bad I get the strong smell of sulfur . and I know Im the only one smelling them, sometime it gets so bad I have to get out of bed and go looking to find out where its coming from, even though I know Im the only one who smells it . anyone one else have this issue ?? or know what it is ???