I just had the last day of my period on the 25. I just want to know why am I bleeding again right now..?

Are you on any hormonal birth control? That can sometimes cause irregular bleeding. It could be a change in hormones, it could be due to a growth, such as polyps. There are a number of possible reasons.

If it continues, or if you have irregular bleeding again, check with your doctor.

I'm not taking any birth control.. before it bled my husband and I just had sex..

Some bleeding or spotting after sex once in awhile is not uncommon. Often due to decreased lubrication, the position, and irritation. If you find it happens frequently after sex and/or there is pain regularly associated with having sex, then see your doctor.