Thank you for the query.
Tampon is not a natural thing. So you insert something that does not belong to your body. Sometimes it can cause an irritation or even an inflammation of the uterine or urinary tract infection
Pain while inserting a tampon can be also a symptom of uterine cancer
With urinary tract infection you may also have frequent urinating and burning while urinating.Uterine infection
can gives bad smelling discharge.
I suggest you to consult gynecologist, have transvaginal ultrasound
. Urine analysis should be also done.
Hope this will help.