I have been having bloody discharges and i don't get my period could i be pregnant the first time i had unprotected sex was last night?

Possibly: It sounds like this may be related to either to the hymen breaking or the trauma of sexual intercourse. Always have protected sexual intercourse as to not only protect against unwanted pregnancy, but to protect against sexually transmitted infections that can lead to embarassment, a lifetime of treatment, pain, or possibly infertility. See your physician if the blood persists or you become weak.

Many causes: The menstrual cycle is under numerous influences, both externally (e.g. Stress, weight changes, diet, etc...) and internally (e.g. Pituitary gland, ovaries, adrenal glands, etc...). Additionally, pathology like uterine fibroids and endometrial polyps can also intervene. Sounds like a thorough work-up is in order. Of course, a pregnancy is always a consideration. Get with your ob/gyn asap.