Lindsay Lohan in Limbo Over Rehab

It's been two weeks since Lindsay Lohan was sentenced to 90 days in lockdown rehab, but TMZ has learned there's been no movement in placing her in a facility.

We broke the story after lots of digging ... there's no such thing as lockdown rehab for Lindsay, and that creates a problem because we're told the judge and prosecutors were under the clear impression -- based on representations by Lindsay's lawyer -- that she could be placed in such a facility in New York.

We're told prosecutors are discussing what to do with the famed defendant, but nothing has been decided. The options are regular rehab (where Lindsay has been a royal screw-up in the past) and jail.

In fact, the sentence is actually 90 days in jail which can be fulfilled by 90 days lockdown rehab.

It's unclear if prosecutors will make the rehab decision on their own or take it back to the judge. Given that the judge also seemed to clearly be under the impression that lockdown was an option, it's likely Judge Jim Dabney will have to sign off.