Spotting between periods

Hi everyone,

I’ve recently taken a break from IVF as I’m just heartbroken and keep having failed transfers. It’s been about 4 months of no fertility treatment. Over the last 2 months I’ve been spotting after sex and in between periods. I’m healthy otherwise and have no real fertility issues it’s basically unexplained. Both my husband and I are clean so it’s nothing of that sort. Any ideas what could be causing this? My periods are on the shorter side to begin with around 25 day cycles. I’ve never had irregular cycles.