So sorry to hear of you mother's passing.
When my grandfather died it would hit me at odd times, like whenever the Judd's "grandpa song" came on the radio...
Took a couple of months for the triggering things to stop getting to me.

If you feel, things are getting the best of you talking with a doctor, is a good idea.

The sticky thread at the top of this forum should have info on the steps of grief that might be helpful for you.
here - http://neurotalk.psychcentral.com/thread3044.html