Voice problem while singing. Remedies?

Hi, For the past one month I have been suffering from voice problem while singing. When I use my chest voice, at a particular range, sound get hoarsed and it hear like a vibrating sound(like a robotic voice) . I have no throat infection or cough or cold. At the initial stage I felt some heaviness above my chest (below throat). I have random headache in right portion of the upper head. My normal speaking sound is fine and not changed, but I find difficulty in reaching some high notes(I used to sing comfortably in high notes)and in using chest voice. I have no irritation or block feeling in my throat. I have been taking steam inhalation for the past 3 weeks twice or thrice a day, to get rid of any mucus problem, if present. But only little amount of mucus is coming through mouth. Can you please tell my problem and suggest remedies? Seeking your kind help. Thank you