I'm married age 25.After marriage periods comes with pain before it was not there.periods comes only for 2 maximum 3 days.blood clotting comes during periods.please advise me that all this is normal or some problem is there.I'm really worried.

How many months of this? By 'after marriage' do you mean after your first sexual intercourse?
Clotting can be normal any period. Pain can be all sorts of reasons. Perhaps your uterus is now inverted. Or you are growing fibroids, or it is just a coincidence with marriage and you are one of millions of women who get pain during their periods. It can even be a first month miscarriage. Are you taking pills or have a IUD or using spermicide? Any one of those could be a reason. If IUD see your doctor right away.