My Left Side Above Stomach Is Swollen. It Has Caused

My left side above stomach is swollen. It has caused me pain periodically and has a burning sensation tonight. I've noticed for several months now it tends to flare up from time to time. I had a hysterectomy almost nine months ago due to several fibroid tumors. My uterus and tumors had attached to my abdomen and bladder and they had to be very careful removing. What could this be and is it serious?