Gmail — gmail hacker identification

Hi this is Karthik, now im in UAE, i have one gmail account
Karthik.[protected]@gmail.com but someone has hacked my password and using my
account. He/she has misused my id. He has used my account in this same time if i
used my account. They sent some of the mails and delete mails from my mail
details. Now i changed my password. But i afraid due to this hacker, my cell no is
[protected]. Sir please help me.
1. How i protect my account and how to know if anybody misused.
2. If possible Kindly provide last 15 days my mail conversation
Please help me, because somebody misused my mail and sent some mails to
others. It’s created lot of problems in my life. So, kindly do the needful at earliest,
because hacker are doing wrong work from my id. I’m waiting for your reply.