Agreed, sounds like your getting a lot of shudder from a warped flywheel/clutch plate or your pressure plate 'fingers' are damaged from too much heat ie abuse It'll feel worse the hotter the clutch/flywheel becomes like heavy traffic.

Go very easy on it for a few weeks releasing the clutch slowly with minimal revs/ load. On some of my cars in the past this has helped 'flatten' the bulged area IF the problem is in hte clutch or flywheelt. If a pressure plate 'finger' is damaged your out of luck.

If it doesnt go away time for a new clutch/pressure/machined flywheel and thrust bearing.