I bought land without a clear title…what can I do?

[Tyler Sample]

I bought a lot for $750 from a retired pastor, he guaranteed me title was clear so did a deed transfer but I went to sell it and could not get clear title. I have a different buyer now that wants it. I’m obligated to tell him about not getting clear title correct? Should I somehow sue the pastor? What can I do to get my $750 back? This was two years ago when I purchased. Please help!