Pericardial effusion after surgery.

I underwent a heart surgery to close the hole in the heart. It's been 6 weeks. At 4th week i felt normal and energetic so that I cn do normal activities and went for walks. From past 2 days i have been feeling extremely tired and sleepy all the time. My BP is normal. I m unable to do normal Activities and cnt get up from bed and feels like sleeping all time I got my 2d echo done yesterday and Pericardial effusion has been detected. The cardiologist said that it is mild. The measurements are 05mm anterior, 09mm posterior, 06mm apical and Basel, 09mm medial. Could you please help me what is the solution to drain the extra fluid around the heart. I am on Dytor 5mg once a day, Embeta 12.5 mg once a day and ecosprin once a day Please advice. What could be the probable cause of weakness and tiredness. I want to be normal and get back to work asap