Lindsay Lohan is being sued. We know, huge shocker there.

This morning's plaintiff is Dawn Holland, the former Betty Ford staff member who got into a melee with LiLo last December, and whose account of what transpired that evening has been murky and ever-changing from the get-go.

According to Holland's lawsuit against Lohan, the star unleashed the fury when she tried to give Lindsay a breathalyzer test at the famous rehab center.

Dawn claims Lindsay Lohan was "combative and violent" when confronted after sneaking off site - allegedly to go boozing - then returning after curfew.

In the lawsuit, Holland claims Lohan grabbed her right wrist, "twisting and pulling it for 8-10 seconds," which caused her to seek medical treatment.

Holland alleges "mental, physical and nervous pain and suffering" from the attack she says Lohan committed, and is demanding $1 million. Minimum.

Here's the problem, though. It's now July. When she filed the initial incident report late last year, Holland never mentioned Lohan's alleged wrist grab.

She also stonewalled an investigation of Lohan at one point, practically defending Lindsay and refusing to cooperate ... then said she was assaulted.

Not to mention, Dawn was fired for blabbing about the incident, basically selling out a Betty Ford patient for a quick buck. Not a credible individual here.