Advice needed

[Lucask]

I've been on noriday for a couple of years and over the last 6 months I had a lot of break through bleeding, I'll have my period then a week later I'll bleed again , but this month I had my period and 4 days after I started bleeding again but this time it's different , I've been bleeding for 10 days but it's super light but so painful I could cry, I went to the doc who didn't seem bothered and said I should have the coil!! How long do I leave it for ??