What Causes Vaginal Spotting After Finishing A Period?

Hi, for the second time after one year I have had spotting just after my period and I am sure this time has been caused by a tampon that maybe I left for too long or maybe it was a wrong sizeI. That tampon hurt me when I removed it. Last year I went to the gp who did all the tests including smear, sent me to the gyno who told me I had thrush and also a bumpy uterus. I was given antibiotics and one canesten pessary. The p Robles was solved in few days. This time I didn't go to the gp but went to buy canesten pessary myself thinking that is is another episode of thrush. The day after the use of the pessary the spotting has become like watery blood and not brown anymore like just after my period. Is this normal? Will this watery blood eventually clear?