hi ...iam dr xxx
is insitu and well within its functional period (usually upto 3yrs) and pregnancy
test -ve,, you need not worry..
sometimes head ache and abdominal pain
can occur with implanon but unlikely now as its been quite some time...
irregular ,missed periods can have multiple reasons like stress
,harmonal ovarian reasons (cysts etc)...consult a gynaecologist ,,,follow the instructions and get back to normal soon..bye