Lost all positions and traffic after adding other languages

Website is 3-4 months old. English version ranked pretty good. At least good enough for customer. Then we translated content into Hindi, Marathi and Telugu. Added hreflang attributes as it's supposed to be. In a few days we lost all positions and traffic we had for English pages. Achieved nothing. It's my first experience with multilingual website, I have no idea what to do, honestly. Thanks in advance for any ideas.