EXCLUSIVE

Britney Spears is in dire straits and a judge needs to protect her ... this according to Lynne Spears, who's acting quickly to make sure her own lawyer can argue her cause.

Lynne has filed new court docs, asking a judge to let her attorney appear at a court hearing Friday in Britney's conservatorship case. At the hearing, Lynne will ask the judge to order Britney's dad to include her in her daughter's treatment plan.

Jamie Spears is Britney's conservator and we know there is an extreme conflict between the 2 parents. Lynne is not asking to become a co-conservator with Jamie ... but she clearly has beef with him over the way Britney is being managed.

Lynne's lawyer says it is in Britney's best interest for her to have a voice in the situation.

As we reported, Britney is not doing well after her 30-day stay at a mental health facility. As we told you, her meds stopped working and doctors have been unable to find the right combination of drugs. As one source said, "Britney is making bad decisions and it's a problem."