How to fix my Iphone 7?

Hello i have huge problem, my Iphone 7 lately starts to crush randomly. Sometimes when im calling someone i can’t hear them and they can’t hear me, also sometimes my camera crashes and I can’t record video or record audio, it works slow( memory storage isn’t full), basically all phone just crashes for a time. But suddenly it gets again normal and i can do all of those things. What to do and how to fix it? Is it some kind of viruss or bug? I have tried to restart it, clean it and do all of those things but it doesn’t work. Also having the latest IOS update. Is there anything that i can do?