You dont have to take diclofenac for headache. You hydrate well yourself and if your weight is above 60 kg , you can take high dose paracetamol ( provided you have no prior
liver problems ).
Prolonged diclofenac , especially during acute illness will do harm to your
kidney.
Next Steps
If your weight is above 60 kg and normal
liver ,
Take Paracetamol 1000mg every 6th or 8th hours for severe headache .( absolutely safe if liver normal )
You can take this dose for 2-3 days
However if you have persistent severe headache , you need to consult a physician to rule out other major issues / post covid complications.
Health Tips
Drink plenty of oral fluids including boiled water