My I Phone getting restart by itself again and again

My I Phone 6 suddenly get restart when i was using it last day, ( This had happened before but it was Ok after 1-2 Hours ) But this time from last 12 hours till now my I Phone is not getting Ok. Apple logo appear for few seconds and then Red color screen appear for 1-2 second, This process is repeating it self from more then 12 Hours and don't know how long it will take further. Please inform how i can get rid of this issue as i really need my phone for traveling purpose. Thank You!