Warning: this is a long post but please take the time to read!
TL;DR
I've read many posts online with people experiencing side effects such as prolonged bleeding, breast pain, weight gain etc whilst on the contraceptive implant. And I know that you can get a prescribed pill to help with the bleeding but I'm still a little worried.. so does anybody have any experiences/advice they can share about their implant?
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I had the contraceptive implant put in last year in May. For the next few months, I had pretty regular periods where I would spot for 5-7 days then bleed lightly for around 10-12 days the spot for 3-5 days. My periods were around 40-42 days apart. I knew that having prolonged periods/irregular periods were a common side effect of the contraceptive implant so this did not bother me.
However, I didn't get my period during the whole month of October and November. I spotted for a few days here and there but never fully bled so I got reaaally anxious. October was already a really stressful month for me as my uncle passed away AND I was also in the middle of studying and sitting my exams during November. So I took 2 pregnancy tests (November 17 and November 21) just to be safe and it came out negative both times.
So I calmed down and went on holiday. But on December 18, I started spotting. I spotted for 2 weeks until December 31 which is when I started a light period. I was on my period for 3 weeks. The bleeding lessened and I started spotting dark brown. Which I assumed was just old blood making its way out -- as I've experienced this during my regular periods before the implant.
However, the spotting hasn't stopped and it's been going on for 10 days now. And for the past few days, I've also been experiencing tenderness in my breasts 
I'm thinking I should make a booking with my family planning clinic (as the GP doesn't usually deal with issues regarding contraceptives in our area) but it'll be at least a week before they can see me.