My period use to come every 28days oct havent got a period.nov i had bleed that was 4days dec i had a period then again at end of the month. is it std?

Irregular periods: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.

Need std cultures: to confirm presence of infection, but irregular periods in themselves are not usually caused by STD. More commonly, if there is an STD, then increased cramping or menstrual flow or vaginal discharge, etc. are more common.