I have been hacked today with 3 btc. Some strange buying and selling has happened has happened. In todays value i have lost 10000 usd. To be honest, i cant sleep now. That is all the money I had.

This happened on bittrex and the worst part is as per bittrex my account was logged in today with just my mobile and nothing else. I use andriod. I get an email notification everytime i login to my bittrex account. I logged in today just once. Immediately after that my account started unsual buying and selling. No withdrawal happened.  I realized this late in the night when all money was lost. Wondering how bittex system allows such hacking. Please suggest what I can do.

P.S i did not f2a. The first thing i will do is f2a all my accounts.