I Just Woke Up To My Pad Soaked Like A

I just woke up to my pad soaked like a diaper thru my underwear and shorts when i went to bathroom it wasnt blood. Im currently on my period so i think. It was a liquid no blood slight smell bc of period watery texture. I recently had my first child in may 2015. I had the mirena put in and its currently been in since june. Had two periods since my birth and labor. This month i started spotting on the third of august. I stopped bleeding around the 3rd day wasnt bleeding for about a week then started bleeding again so i assumed i got my period. Just tonight this liquid happened. Im not sure where it came from but im guessing it was my vagina. Slight mild cramping in lower abdomen no other sympthoms. Im slightly worried what it could be. Im 26 decently healthy i have unprotected sex but no ejaculation inside. I am on the mirena. Should i be worried?