strange symptoms 😕

A
So I had my nexplanon implant out on 27th October. I had my first period 27th November followed by a two day bleed on the 27th December. (They normally last 5 days at least) 
I'm due to ovulate any day now according to glow but I'm having sharp pelvic pains and killer back ache. It feels exactly like I'm about to start my period again...plus I've been having a lot of unprotected sex for the past few weeks...
Just wondering how long other peoples periods took to go back to a regular cycle? I know it won't happen straight away but it's starting to annoy me not knowing now hahaÂ