The industry accepted help documentation tools are RoboHelp, FrameMaker, and MadCap Flare.
However, these tools are very expensive as compared to "Screen Steps".
I would recommond you to go for free trial of "Screen Steps" and check you comfort level with it.
Given that you are creating a database. You also have the option of setting up a table where each record is a help article and you use the same scripting, buttons, etc to search this table and bring up help articles. Not only does this eliminate the "learning cycle" involved in using any new application, it makes it very easy to setup help buttons or menu options that are context senstive. Click a help button on your data entry screen and see a help article on your data entry screen, for example.