nikonmom, Before going to the expense of lining your chimney or getting someone to build a new chimney, contact a chimney sweep and have them clean and inspect your existing chimney. Cleaning and inspection usually runs in the $100 or so range. If you want it a video inspection that may be a bit more.
It may just turn out that your existing chimney is good to go and you don't have to do anything else.
I recommend you get someone to clean and look first.
Rev. Larry