Ladies, the implanan (birth control)

Ok, this past October I got the three year birth control implantation. I still have my menstrual cycle (which are way less severe); however, I lost 15 pounds and when I went on vacation and came back, within three weeks, the pounds were back! This has never happened before. I know I changed my eating because I was on a trip; but I think the weight gain was too rapid. Have any of you all had this problem, and do you think the birth control was/ or could be the reason? I think I'm getting this sucker taken out! lol