The Fluid After Lipoma Removal Has Turned Very Hard and Produce Sharp Pains Sometimes, Normal?

What your describing seems like a hematoma.  A hematoma usually starts out as a fluid collection and then hardens over time.  Given more time, the hematoma is automatically broken down by your body.  The hematoma should resolve on its own, however he should follow closely with her plastic surgeon to ensure that you do not get infected.

it sounds like you had a hematoma form after lipoma removal.  After drainage of a boil, removal of a cyst or lipoma a cavity remains called a dead space.  Blood and body fluids can collect in dead spaces cause pain and infection.  It sounds like you need to back to your surgeon and either have the area punctured and drained with a needle or perhaps even opened up and debrided if the material is solid.

This is probably a blood collection that clotted in the cavity, that is why it is hard, gradualy the blood will become softer and can be aspirated.

The other possibility is to reopen the wound, clean the blood and close with a drain or quilting sutures