IPhone 5 battery messing up?

Ok so my iPhone 5 is only about 5 months old and for the past 2 or three months the battery is being weird. The battery level goes down really fast sometime and now the new thing is to turn off at random times. Yesterday it was on 50% battery and turned off wouldn't turn back on it was giving the connect to charger sign i plugged it in and it immediately turned on and said 43% so obviously it wasn't dead It still continues to do that at random percents. I restarted it holding down the home and lock button and removed the sim to check for water damage. So what's wrong with it. And another thing if i need a new one covered by insurance are they gonna give me another 5 because my friend had to get the 5c when hers got lost

Assuming your iPhone is still under the 1 year warranty. You will get a replacement iPhone 5. Since they stopped producing the i5, you "might" end up getting a 5S, but that is not too likely since they keep a bunch of stock 5's. Don't worry, take it to the Apple Store and tell them what's happening. Since the battery is hard to replace, they won't go through the trouble and probably end up giving you a replacement. My i5 had an unresponsive home button, but since I wanted a brand new one and didn't want them to just replace the button and scratch it up, I grabbed a hard drive magnet and passed it near the phone for a few seconds, which completely friend it and it would not turn on. Went to Apple Store and said it died while I was on the phone, they hooked it up to the machine in the back and when even that could not turn it on, they gave me a brand new iPhone 5. I love warranties. Hope this helps