What could cause a litte bleeding for one day(not period),and after some days the same event?could stress and anxiety do that & even delay nxt period?

Stress: Stress can certainly cause changes to your period, even delay the next period. If this is a persistent problem, see your doctor for evaluation.

See below: Abnormal menstrual bleeding is often due to an alteration in the normal cycle of hormone release from the pituitary gland, which can be due to stress/anxiety, as well as many other things. In the majority of cases no underlying illness is found. Just to be on the safe side do a home pregnancy test and repeat in 1 week if negative. For more information on spotting go to http://bit.ly/1CnC9xV