Sageretia - leaves turn Brown, help!

[Searching help for sagere]

Hello I am new here. I got small sageretia as a gift. Have it 2 months, firstly it Has many new little leaves and grown, but now sth was happend and my tree leaves turn into Brown... And dont have new green small leaves please help , somebody here knows what is going on?
Pictures below

 

[NOZZLE HEAD]

Has the tree recovered? How often were you watering.