Most common causes for burning and slippage are wear or oil leakage onto the clutch disc. Hydraulic failure has a different set of symptoms. Usually the difficulty is getting gears engaged or disengaged.

Dry slippage, usually due to wear, "riding the clutch" (keeping your foot pressed slightly on the clutch pedal keeping it from engaging completely) or some mechanical reason with the arm or throw-out bearing that keeps the clutch from fully engaging generally smells more like burnt cookies than fish, but then I don't know how you prepare your fish. With the possible exception of the "riding" scenario, it does not heal or get better without some attention.

Something leaking onto the clutch is either coming from the engine (rear main seal) or transmission (from the front bearing housing). It becomes fairly obvious as the bottom of the bellhousing and trans will become wet with oil, usually well before any clutch problems.

Oil can burn-off and improve, but only if the source is stopped. If the front seal of the trans, it could mean you are now low on oil in the gearbox. Good reason for running hot and/or noisy. It will cool down, but ultimately beat up again unless refilled, but will leak again unless addressed.

Check under the car for leakage, wetness along the bottom and oil now dripping onto your driveway. Also check the engine and transmission oil levels, though I would more suspect the transmission as the source if it is oil that is leaking.

One last thing - is the engine running hot? Check the coolant level. There's the possibility it is coolant on the clutch coming from a head gasket or other failure, that could smell kind of fishy when heated. It would also evaporate quicker than oil and return to near normal operation once gone.