Earnest request to help me out.....

Hi doc,this is neel..i am a guy of 25 yrs.i am in deep trouble & need ur help desperately..i have been a smoker for the past 7 to 8 yrs with an average smoking of 8 to 9 ciggi's daily..but i have quit smoking a month ago b'coz of my voice and breathing issues.doc ,i am in the profession of singing for the last 3 yrs but recently i have noticed that my voice quality is detoriating and the flexibility level has gone down to a huge extent.it always feels dry inside and a cough sought of thing in my vocal channel every now and then along with the a bit of hoarseness. i am missing that volumnous voice of mine.. its getting thin or may be shrill..i have consulted a doctor but he gave me some vitamin c tablets to chew which hardly helped..Moreover my breath control is also suffering a lot..i am not getting that proper flow of respiration while singing..i literally need to pull the air upwards and it gives a heavy feeling on my chest portion...apart from this i have always maintained a good healthy body and lifestyle...i have taken good care by doing yoga's and other exercises regularly along with quality food..but this voice hoarseness & respiration issue is now irritating me so much that it has messed up my mental stability.i am really really depressed doc..plz plz plz help me out..i can' think of living without singing.. i want to get my voice back..plz plz plz...i am really counting on u...