Brief Answer:
Information
Detailed Answer:
Hello and welcome,
Without being able to examine you I can't say with absolute certainty what this is but I can tell you some likely possibilities.
This could be a cervical polyp - a growth on your cervix. If it gets big enough, it can cause what you described. The majority of cervical polyps are benign, and can usually be removed in an in-office procedure by a gynecologist.
Tissue from the lining of your uterus that was retained in the vagina after a recent menstrual period is a possibility but probably less likely as the way you describe this sounds like the tissue is attached to you.
While you are on the younger side, if you have had babies, it is possible that this is a prolapsed uterus. This is where the ligaments that hold the uterus in place allow it to move down into the vagina, and in more severe situations, even out of the vagina a bit. There is a feeling of bulging/pressure usually. It is usually worse when there is increased abdominal pressure such as with sneezing.
Other possibilities are an infection (but you did not mention discharge, so less likely) and growths in the vagina or the hymenal ring where the hymen used to be.
The only way to really know what is going on is to go in to be seen and have a vaginal speculum exam. But hopefully having an idea of what the possibilities are can get you started.