Talk to Ent Specialist on Voice Quality, And Voice Cracks

My voice quality was very good. It was very well admired while speaking (presenting, voice overs) and singing(song, naats) as well. Though i always had issues when i spoke for longer period, my throat starts to hurt amd voice starts to disappear after continously using for 2,3 hours. But after rest it used to get fine. Now the issue is after teaching for 2 years(left teaching now, its been 3 years now) my voice got really bad. During every sentance i have to clear the throat, jaisy khungharna. How can i fix this issue? Is there anything in medicine which can help me in this regard?