Most people experience some hair loss as they get older. There are a lot of factors that may be contributing to a pronounced loss of your hair in your particular situation.
Are you on any medications? How is your diet? Are you eating plenty of protein? Have other women in your family experienced this at your age? This article may help and give you a general overview of menopausal "hair" concerns:
http://www.redhotmamas.org/newsletters/newsletter_200507.html#2
Can you blow dry your hair in a way to conceal the thinning? Can you get a haircut that will hide the spots? Just stay positive- there are a lot of ways you can cover-up thinning hair!