I had unprotected sex 3weeks ago just after my period.1 week later had a today period. Now I hv nausea and mild cramps. Couls I be pregnant?

Just need to clarify. What's a "today period". Do you mean you got your period today?

If you've gotten your period then it's unlikely that you're pregnant, but if you're concerned then try taking a pregnancy test. That's really the only way to know for sure.

Of course pregnancy is always a concern whenever you have sex, especially if you have unprotected sex. So I'm going to assume that you're trying to conceive. If not, then you should at least lower the odds by using some form of birth control. Two is better. Even then pregnancy will be possible, just less likely.

If you keep doing what you're doing now, it's only a matter of time before you do become pregnant.

Good luck.