Wow, I am having about the same thing! I am one month out of having my RNY. When I got home, I noticed the my large incision on the left side was leaking a lot if fluid, so I went to see my surgeon, and he told me that I had a seroma, and he was going to drain it. He took out a small amount of fluid, and soon after the incision healed up and stopped leaking. I thought that was the end of it. At my two week post op, the doc said that I still had a bit of seroma there. But that would go away. I had to see my pcp, and she said the same, so I assumed everything was ok.
Then, last week, I noticed a small lump above the incision. By last Friday, it had grown and now the lump was visible, and was hurting a little, not too much, but it was bother some. By today the lump was even bigger and hard to the touch, so off to the doctor I go again. He did an ultrasound, and saw some bowel and a small pocket of fluid. He said that maybe it's just a large hematoma, so he numbs up the area (numb my a$$!) and sticks in another needle see if he can get anything out. He says, it just blood in here, and he shows me the syringe, which has about two drops of blood in it. But, just to rule out one or the other, he is ordering a CT scan, also to look for a possible incisional hernia, so they are trying to schedule it for tomorrow if possible, and I go back in two weeks to go over the results.
What's crazy though, is that now this thing hurts like a mother! I guess it's from all the prodding and poking and needles. I took some pain medicine, and have an ice pack on it now.
Anyway, it's weird that I came to post about it, and the first thing I see is your post! Keep us informed, i' curious to know what the results of you CT scan are, and what they are going to do about it.
Take care and I hope that everything works out for you!