I had a unsafe sex before three months.
I took pills with in 24 hours.
I had regular periods for three months.
Now I am continuously vomiting for two days.
Is that a sign of pregnancy?

If you have been having regular periods then it is more likely a sign of being ill. If you are concerned about a possible pregnancy, and want some peace of mind, try a pregnancy test.

Nausea can be a sign of pregnancy, but is more likely a sign of some illness. Plus the first manifestation of pregnancy is a missed period. If you have not missed a period then its due to something else.

First there is no such thing as sex that is completely safe of pregnancy. So are you still having SEX ? Even safe sex ? If so, you could now be pregnant from sex this month.

The first and main sign of pregnancy is a missed period. So if you are not missing a period, then no you are not pregnant