I've been on implanon for 10mos now and have had no periods til the last three days i had little spotting that last three days. could i be pregnant?

Yes, but uncommon: Iud properly placed can be high effective..Such as Mirena (levonorgestrel) which touts over 99% efficacy/protection from pregnancy. Implanted Implanon claims same. Thus, your chance of pregnancy with a correctly placed and funtioning Implanon is very low...These however, can change your periods. If having symptoms of pregnancy though, i would suggest a home pregnancy test or consult your doc for eval... Good luck.