Milky Discharge, leaking down my legs.

Hello Everyone, 
Hope you are all having a lovley day or night.
I just experienced a discharge from my vagina running down my legs as I got undressed to get a shower. It looked cloudy almost milky. 
I finished my period about a week and a half ago, but last night had some blood when I wiped. I do have and IUD (Mirena) and know that this is a common side effect. I am sexually active and did have sex last night with my boyfriend. I am 19 years old and do have an IUD. 
I am so confused as to what this could be. I have been feeling really crampy, headache and nausea. I have also had this Mirena since January this year. If anyone know anything about what I am experiencing or what it could be it would be much appreciated. Thank you in advance.