How to get my voice strong like Janis Joplins? 10 points?

I know I will never be able to sing Just like her or anything like that lol But I wanna be a rock/ Blues singer like her someday.( I liked singing for years( im 14 year old girl) bu Janis really pushed me into it a lot more. I have a problem though: my lungs and throat are messed up I cough up stuff sometimes and90percentt of the time I cant get it out and if i just drink lets say I had blue powerade after drinking it i will cough up blue stuff. and i have a hard time breathing through my lungs my doctor( been there twice butdifferentt doctorsIggyh some doctors seem to think antbotics cureverythingng) put me oantibioticscs but it never works. I plan to see a doctor soon but i dont think they can do much other than that. well if i do ever get better( haha) how can I get my voice strong? o yeah and i sang in school fromkinder gardenn-6th grade but i quit because I got sick of the teacher she was kind of a ***** even inKindergartenn she always yelled at us for acting up sometimes and called us immature we werekindergartnerss for godsakes! lol OH YEAH AND NO SMARTS *** ANSWERS ABOUT JANIS! LIE DONT BE SAYTNG STUFF LIKE OVERDOSE ON HERION , OR DRINK WHISKEY AND SMOKE CIGARETTES HER VOICE WAS ALL NATRAL SO THEY RASP SHE HAD SHE COULD TURN ON AND OFF LOL