Hello, There are several factors causing the discomfort when using a tampon including: 1. Incorrect insertion - if the tampon you use is not inserted adequately, it may not position comfortably inside the vagina. Try to change position and ensure correct insertion. 2. Observe for dryness: Take note that sometimes vagina might be not wet enough or the amount of the blood is not enough to fill in the tampon. This might be associated with a bit of discomfort while inserting inside the vagina. Check for the blood / discharge amount and see if this corrects your discomfort. 3. The vaginal opening skin is very sensitive. When inserting the tampon, sometimes its ring can cause friction against this sensitive vaginal wall, giving the discomfort sensation to you especially when moving or sitting. 4. See if you have changed the brand of tampon used. Sometimes, its ingredients might cause allergic irritations with discomfort. 5. Take note about the time when tampon was inserted. The longer, the more discomfort you might feel as it might dry inside and might cause a little of inflammation. 6. Check for possible vaginal infection or inflammation. If present, it might cause the discomfort while using the tampon. Most probably in this case you might need to get a physical examination by a gynecologist and run vaginal swab testing to see if infection is present and treated adequately. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Albana Sejdini, General & Family Physician