Hi,
Welcome to ehealthforum,
You should consider visiting a gynecologist/obstetrician to get examination done especially to rule out chances of imperforate or thick hymen or vaginal structural anomalies (if you have been having pain/discomfort since the time you became sexually active). Other possibilities include infection, structural anomalies, internal injury, vaginal dryness, mental blocks, probable vaginismus, etc. Visit your doctor/gynecologist for further evaluation and assistance. Get started on treatment as indicated by examination and evaluation/investigation results.
Take care.