I don't know if this is normal or not but almost every time I have sex, my period starts again. Sometimes it only lasts a day but others it's a couple of days. I am on nexplanation (the implant) birth control. It has caused my periods to be pretty irregular so I don't know if it's just from my birth control or if something is actually wrong. Has this happened to anyone else? And if it has what do you know about it?