Mum is starting Erlotinib. Anyone had good results?

Hi, my Mum is starting Tarceva Monday after previous chemo was unsuccessful. She's very weak & breathing is getting worse. She was only diagnosed Nov but the change in her in huge. She had radiotherapy on a lump on her side last week but feels this has made no difference. Her confidence has been shattered by lack of positive results, it seems every time she has an appointment there is more bad news. We're all struggling to cope, my Dad is her main cater & I know he's terrified of losing her. Mum has so much to live for & until Nov was leading a full & happy life. Has anyone had experience of Erlotinib? It breaks my heart seeing my amazing mum, my best friend suffer so much. I want to make it ok for her & I'm desperate for her to be well & to enjoy my 2 daughters like I know she would love to. This is the worst time of our lives, I can't stop crying today.