Fluid and pain from Lumpectomy, Why?

I have had a lumpectomy with sentinel lymph node procedure in April, and the breast that I had the surgery in has a lump that feels like a brick.  That's how hard the lump is, which is also a pretty nice size.  Later, I found out through an ultrasound that it is from fluid. The surgeon will remove the fluid when my chemotherapy is completed. Some days the size is not as big as other days.  When I press on it, it feels numb. There's also shooting pain from time to time.  Is there anyone who has gone through this or knows anyone that has had the same symptoms that can offer me advice?  This becomes very uncomfortable at times and it makes me wish I had opted for the mastectomy.      

[Cheerpul]

Any time tissue is removed from the body, for instance with either lumpectomy or mastectomy, the body attempts to fill the space with fluid.  It is called a seroma.  Draining it is done with a needle which draws the fluid out of the cavity.  I had my mastectomy site drained 4 times, the first was a huge amount and each time was less.  The pain and discomfort was pretty sharp, when full was hard, and was almost instantly relieved by drainage.  The fluid will stop building up when the tissue around the site "sticks together" and no longer allows fluid to pool in that spot.  The fluid that is left will gradually thicken and become firmer and actually makes some contour to the area.  Also, after this amount of time, your body may be already reabsorbing some of the fluid and that may be why some days are better than others.
It comes down to this: When there is too much fluid, it is uncomfortable and painful.  When there is just a little left, it is not a bad thing.  Talk to your surgeon and oncologists to let them know how uncomfortable it is and if they have any suggestions.  Also, I had 2 different surgeons do my drainagees - one who used a lidocaine injection before and one who did not.  Ask for lidocaine, it made the procedure almost painless. I am thinking of you.