My mom passed away in December

My mom passed away at the age of 58 from NSCLC on December 7.  She had never smoked a cigarette in her entire life.  We still aren't sure where her cancer came from.  She lived 20 days from her diagnosis.  They tried chemo and radiation and nothing helped, we knew that at best it would be palliative.  She and I were extremely close and it was very sudden.  The past week has been extremely hard for me.  I have been very depressed and emotional.  I thought I had gone through the stages of grief months ago but now I just can't quit crying.  I had been doing well in March and at the beginning of the month but then all of the sudden it is like I cannot control my emotions.  I cry more than not.  Has anyone else experienced this?  Also, and this will likely sound very selfish, but I also worry that I will die from it or some other type of cancer a lot.  Probably irrationally so.  Has anyone else experienced this?  Sometimes I think I am just having a difficult grieving response and being selfish by worrying about that.  I just want to know if this is a "normal response" or if I am the only person experiencing this?