swelling in chest area

I have had a bulge in my chest for a little over a year. I had assumed it was a hitial hernia. I just did gerd tests and dr. said it wasn't a hernia that is bulging from my chest. Now I am worried about what other possibilty it could be. It has gotten bigger in the last two months sometimes it feels like fluid other times it feels a little hard. I also have pain radiating from that area. It is located in the middle of my chest and in between the breats. I am 51 year female and about 50 lbs overweight. Anyone have this problem or know what this may be?