Hi ,
Because of cold there will fluid that is mucous thats collected behind your eardrum called tympanic membrane. When you did Valsalva the fluid entered the tube btw nose n ear . Because of this there might be decreased hearing because of fluid.
But you should also rule out sudden sensorineural hearing loss due viral aetiology and other and cause sudden hearing loss .
If you feel there is discharge from your ear then there might be perforation.
Next Steps
Pure tone audiometry this will help to differentiate from sudden hearing loss and is there fluid in middle ear .
Antihistamine, mucolitics and nose drops n steam will help you out .
Better to visit ENT clinic for examination
Health Tips
Hearing test .