The rod

So I got the rod in 2016 I’m on my last year of it, and I got my period for the first time in 1 year about 2-3 months ago and it lasted for 2 weeks. The last week of it it was really light almost just spotting and then it stopped. About a week and a half later I got it again and it lasted about 4 days and then I got it a month later and it only lasted a normal 5-6 days. When I first got it my doctor said it’s just break through bleeding but now he doesn’t know why I’m getting it all of a sudden. Has this happened to anyone ? I’ve taken pregnancy tests and they come up negative so I’m not pregnant it I’m not sure what’s going on. i’ve been given the option to go on the pill as well a the rod or get the rod replaced and I don’t know what to do. Please help! X