Yes, your Dad needs to be examined before he loses his voice.
Next Steps
Using your smartphone's Practo app, search for me under ENT Doctors in Bangalore. At the bottom if my profile page, you will get 2 links. One is to book an appointment to meet me at my clinic. The other link is to book a Video Consultation with me.
Health Tips
Have a small torch and a spoon ready to press down your dad's tongue so that you could use the torch to show me the back of his throat during the consultation session.