How To Get Rid Of Irritation In Throat, Coughing Spasms And Hoarseness?

I had an EGD about two and a half years ago, and while under, my O2 sats dropped to 50. The egd tube was pulled out quickly and I wound up with aspiration pneumonia. I wound up seeing an ENT due to a cough that wouldn t go away (woke up from the EGD with coughing spasms and difficulty breathing) and he said that the muscles near the vocal chords had been damaged. Since then, I will have episodes that last up to three months of having a irritation feeling at the bottom of my throat, coughing spasms, and hoarseness. This has effected my voice when I sing, and a lot of the time the sound just won t come out. What should I do? I had never had this kind of problem before. Some people say it sounds like allergies, others say asthma. It is very frustrating. Please advise. Thank you