Britney Spears is having some family bonding time with her mom – but the pair have been seen arguing, according to sources.

Lynne Spears, who arrived in Los Angeles Monday, accompanied her 26-year-old daughter and pal Sam Lutfi to a Mercedes Benz dealership in Beverly Hills Tuesday morning – but it was not exactly a happy family outing.

"Lynne and Britney were arguing in the car the whole time. They're both upset and arguing, not having a good time at all," an onlooker tells PEOPLE.

After 15 minutes at the dealership, Britney drove a black Escalade off the lot. "After she came out, she pulled over to the side of the road to argue with her mom more," adds the onlooker.

The previous night, Lynne had visited her daughter's home, but then was left to pace around the house after Britney left the house to meet Adnan Ghalib.

“Lynne, at one point said, 'I just want to give her a hug. I'm very worried," says a source. "Lynne was so nervous and worried, she just kept asking how they could get her daughter back home."

When the pop star did return home, Lynne, Britney and several friends including, Alli Sims and Sam Lutfi, had a "family bonding session over a lot of things," says the source.

But the family time does not seem to have changed Britney's behavior. On Tuesday afternoon, she and Lutfi visited a nearby J. Crew, where an onlooker described her as "totally out of it."

"She was talking in a slight accent. It was a little of a British accent," says the eyewitness. "She kept to herself, quiet, she just wanted to go. She really wanted some Bubblelicious gum and she kept asking Sam for it and got frustrated when he didn't have any. Her mood lifted when she found some in her bag."