Why do I have a burning sensation in my abdomen when milking my tummy tuck drain?

I am 9 days post op mommy makeover and have one drain out of 2 remaining from my tummy tuck. My problem with this drain, for about a week now, is that there is an intense burning sensation on the opposite side of my abdomen from where the drain is after I finish milking it. It is mid-right abdomen and seems to be intensifying as the days go on. My last post-milk brought me to tears it was so painful and intense. My recovery has been smooth sailing so far. What could be causing this?