Ay, ganyan talaga minsan with injections, ang hormones natin kailangan ng time to settle, so ongoing spotting for months after is possible, but honestly that's quite a while na po since December, kaya best to check with your OB just to be safe na wala pang iba pang nangyayari sa body mo. A few of my mum friends who switched birth control methods also experienced spotting for weeks or even months, but if it's been this persistent, it's really worth getting checked so your doctor can rule out anything else at maybe suggest a different contraceptive if needed.