Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
Mometasone Furoate is a steroid based cream. Steroid creams initially shows wonderful effects on face by reducing pigmentation and brightening the face.
But long term use has severe side effects like skin thinning, pimples, inflammation, rashes, itching, excess hair growth, and dilated veins under the skin.
I would suggest you to 
consult a Dermatologist who can evaluate you clinically and also advise you to taper down the application of steroid cream and gradually stop using it.
For reducing the dark spots, you can start using safe 
depigmentation creams and facewash like 
salicylic acid and 
glycolic acid containing facewash, 
kojic acid, arbutin and glycolic acid creams etcetera.
You can apply cooled aloevera gel on face to soothe the skin.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Honey Arora