Lymph node removal and Seroma?

I had my lymph nodes removed along with my left breast, 2 months ago. Now I am struggling with "leaking" water from my underarm! I called the hospital immediately and they said it's something called Seroma and that it's not dangerous and will most likely go away on its own. Does anyone have experience with this? Still a little freaked, even though the nurse said it should not be a problem.