Hi! I Have A Burning Sensation And Itching Inside My

Hi! I have a burning sensation and itching inside my vagina since few days ago.. I'm urinating frequently, with a burning sensation and difficulty. Few days ago i slept with a tampon for more than 12 hours and i had really bad burning sensations after i took it off in the morning, but im not sure if this is the reason.. What it could be? What i should do?