I get something similar, I have to have laundry detergent around me so I can smell it or just be comforted by it. It's weird, and strange. But yours sounds like something that could hurt you.
Most likely, a deficiency of some sort. *shrug* I dunno, just a guess, I'm no expert. For all I know, it could be menopause or a mid-life crisis.
iNow, brain tumors would cause personality changes. This is a sudden craving. And it's not rational to assume the worst before eliminating the most common reasons.
Pica, huh...? So you have a craving to eat objects that you shouldn't eat? I had that slighty for a short while when I had iron deficiency. That could cause it, as well as a tapeworm. It's best to assume the most common things before you start freaking out about a brain tumor that you most likely don't have.
See a doctor, if it's a tapeworm or a deficiency, then it needs to be taken care of. If it's psychological, then see a psychologist. Point is, you most likely will not get a diagnosis without flaws on the internet, especially if it's an amature diagnosis. See a doctor. Like ASAP.