After her periods we had sex for a week and after three days she told that she is suffering from slight headache and also she is showing the sign of vomiting. So please tell me is she really pregnant or not Or is this two sign are the early sign of pregnant?

Wait until she misses her period, then ask her to take a pregnancy test.

Don't go on symptoms, they could be any number of things.

3 days after having sex is usually too early to start experiencing pregnancy symptoms as if the egg has been fertilized it usually hasn't made it's way down to her uterus yet to implant and start releasing HCG and start the signs of pregnancy.

I agree with Capuchin and wait until her missed period... if she does in fact miss. And if she is worried about possibly being pregnant, her body can produce the symptoms from her paranoia... and severe headaches can cause vomiting... if her headache persists I would have her go see her doctor... as is may not be pregnancy, she may just be sick.

Most women don't show any signs of pregnancy until they are at least 6 weeks along. What you are describing sounds like the flu to me. But everyone else is correct, wait until there is a missed period before getting worked up. These symptoms are common symptoms for many things.