I had unprotected sex a week ago and now I'm cramping what does this mean??

It means you are having cramps? No one at all on the internet or perhaps even a doctor if it is pregnancy, can tell you what it is at this point.

Of course you had sex, and it was unprotected, so yes there is a good chance at pregnancy and this could or may not be a sign. You won't know that for a few weeks till it is time for your period.

It could be from the sex itself, if you are not having sex on regular basis. Could be from an infection or even a STD.