Advice???

So I have the IUD implant and have done for about 2 years and a couple months. My period have always been random, never really know when they’re coming they just pop out of nowhere but always only last 5 days and they’re not usually every month. This time I had my usual 5 day normal period and then less than 2 weeks later I had more ‘spotting’ I guess. No cramps, no other symptoms and again lasted about 5 days but was paler in colour. Not dark like old blood, cause I thought it might just be older stuff flushing out but it was more like a light pink

What could this be?