Dieing leaves very slow growth HELP HELP

My plant was growing just fine and fast then i started gettin yellow leaves the last few days after they turn yellow they turn brown and die. im using schultz 10-15-10 plant food every 3 or 4 days for now thats all i had the money for atm. im not sure if its calcium deficiency or over fertilization or something else. I know someone can help.
Thanks!!!!