Swelling (5 days post op)

Looking for info....I had immediate swelling in my belly, particularly in one area....right side just under breast, rib-cage area. It's quite pufffed up above the incision. Internist looked at it before discharge and said it's Water, it will go away. My problem is, I'm having a pulling pain in that area that also affects my back muscle. It's like a muscle cramp, and that's just what I think it is. Looking for suggestions to help the water retention evacuate. It hurts if I sit upright too long, and if I lie down it goes away immediately. I called surgeon's office, explained, and they just issued a stronger pain medicine. Just take the medicine and wait it out????