My Boyfriend Just Told Me I'm Boring On Bed, What Does it Mean? [ADVICE]

I caught my boyfriend searching on Google '"My girlfriend is so boring in bed. How do I tell her?"
So I asked him what's up and he, pomp and plain, told me he is not satisfied with our sex life.
I can't even tell you how much of a blow that was to me.  I was absolutely gutted. I didn't even know whether to cry or beg him.
I know I'm not the prettiest girl in town and I don't feel comfortable flirting around, or things like that.
But I know I'm a very good girl, I try!!
What the hell can make someone not boring in bed? What can I do now?