5 month old iPhone 5 freezing and power button broken. Is this a reoccuring problem?

I bought my iPhone 5 this past November and use it regularly. I probably have about 20 apps on it and maybe 200 songs. I use it to text on a regular basis. and occasionally i use it to look things up online. About 2 months ago my power button stopped working. I could no longer lock my phone or take screen shots. I would have to wait for the phone to lock itself after a minute because the button did not function. Thankfully my boyfriend showed me the assistive touch button so now I can lock my phone, but the power button is still broken.

More recently I have been experiencing a lag in my phone. When I try to type in my password on the lock screen it freezes. I also do not always get notified of new SMS messages coming through my phone. I have to manually unlock my phone (which could take a few minutes if it decides to freeze) and check to see if I have received a reply. (Kind of annoying when I'm holding lengthy conversations).

Has anyone else gone through this with their phone? If so, is there a way to fix it (without doing a hard reset because my phone won't turn off... or back on).

Thanks.