Gomez is said to be annoyed with Bieber after he has spending time with model Barbara Palvin, reported Showbizspy.
"Her up-and-down relationship with Justin Bieber is taking a toll and she looks thinner than ever. She isn't eating because she has so much anxiety about Justin being faithful and doing right by her.
"Selena's freaking out. She's stressed about the fact that Justin's added more tour dates and they'll be apart for longer. She doesn't trust him," a source said.
Recent reports claimed Bieber is exasperating Gomez's health woes with his immaturity. "She's in a bad place. Nothing ignites Selena s health issues like Justin s immaturity," a source had said.