I have read that I actually do have pica, but it's hard to quit?

Pica causes. Pica is diagnosed on basis of persistently eating something of no nutritional value for greater then one month and is developmentally inappropriate. It is usually due to mineral deficiency in the usa. The desire to quit is strong in some people and both mineral replacement (e.g. Iron supplementation) and behavioral therapy have proven successful. Recommended that you be seen by your primary doctor.