A story dies in its infancy

For Christmas, my brother bought me a Stephen King novel called Cell. I couldn't put it down and just finished it about an hour ago. I have to say it was a magnificent story, albeit one with a lackluster and almost disappointing ending. I just wanted a bit more of the story, but my imagination can fill in the blanks.

The biggest problem I am facing now is with my own story. The basic premise and plot outline are very similar to that of Cell, and I don't want to continue with my own story now out of fear of unintentionally incorporating King's work into my own (or being accused of doing so intentionally).

King's principle: An unidentified cell phone signal makes people lose all of their memories, conscious or otherwise.
My principle: A terrorist chemical attack makes people unable to distinguish between their memories and other information in their brains.
Similarity: Everyone affected goes crazy and the world is plunged into chaos.

King's plot line: A single and highly unlikely hero travels across states to save his son from Armageddon.
My plot line: A single man travels across a horror-ridden city to save his lover.
Similarity: Unlikely hero traveling a great distance to save a loved one from turning into a mindless zombie.

I can't keep writing this now. Even if I did, it would seem too much like King's work and either no one would read it, or I'd have to find some way to prove I didn't steal his idea. Considering I've now read his book before finishing my own story, I think that'd be kind of hard.

So, if anyone has another plot idea for a short story, please let me know. Until then, pick up a copy of Cell; it really is a good book.