Former NBA star Lamar Odom is staying sober and feeling better after spending weeks in a Vegas rehab … this, according to sources close to the situation.

We’re told Lamar is “doing really good” and “feeling amazing.”

An insider tells TMZ … “This time was different because Lamar checked himself in,” and says the athlete’s family and friends have been extremely supportive.

We’re told Lamar has about a week left before he completes his treatment program.

Once he’s out of rehab, Lamar will have to deal with his DUI criminal case … the NBA legend — who is feeling a “little worried” about the case — hired attorney Michael Becker to represent him in court.

As TMZ first reported … last month, Lamar was arrested for driving under the influence while driving around Sin City. A police report said Lamar’s car reeked of weed.

Following his arrest, Lamar told us he was not under the influence of narcotics, saying … “I am learning from this experience and remain committed to my continued growth.”

“I’ve worked hard to rebuild my life, and taking responsibility is an essential part of that process.”

He continued … “I am cooperating fully, staying honest, and focused on moving forward with integrity. Thank you to those who continue to support me.”