Thanks forthe practical question, let me answer to it preciselyto the point. Bleeding during and after intercourse in situation like yourswhere tampon is inside depends on the 1,the day of menstrual cycle you are in, the amount of menstrual fluid discharged from uterus, size of the tampon and force of penile thrust on the tampon while having intercourse.
Normally it may not bleed heavily at all.But the concern is keeping tampon for long inside the vagina,Which can cause infection giving rise foul smell. I would suggest first of all not to worry.clean properly thee vaginal walls inside with lukewarm water.still persists a foul smeeilg and if you are getting fever meet thegeneral physician for antibiotics and vaginal douches.Best wishes.