Random beeping with link popping up

So I was sitting at home, and randomly my phone (iphone 6s +) starts beeping with a really weird and creepy high pitch, never ever heard anything like this before, and pops up a "message" on the screen with a link. (the beeping sounded something like this just shorter beeps and it was constant 10 HOUR BEEPING - YouTube)

I managed to take 1 screenshot before it stopped after 15 sec.
after it stoped I was pretty confused but went on with watching tv, and literally 3 mins later it hapened again, same thing just this time with another link, and I managed to take 3 screenshots now so the whole link can be seen

So the second time it was a different link and I actually swiped the "message" with the link right, to see what happened, but it just got into the menu and nothing happened...

Now I have to tell you that my phone never ever did anything wierd untill a few weeks ago when I upgraded the newest IOS...
I bet a lot of you will think that im crazy for believing that this has to do with anything, but my phone always worked perfectly and since the IOS upgrade it freezes alot, even my battery is doing weird things like loosing 1% charge/second (no this is not a joke) and stuff like that. Last week I had my phone on 95% and 10 min later it was on 17% and dropping 1% / second, untill it reached 4% and then it stayed on 4% for 2-3 hours....
Sometimes my phone opens the menu really slowly, or it doesnt even open, and last time it had no sound until I restarted the whole phone. Really weird and this all since the latest update.

What Can this be?

Is this some kind of virus? anyone had similar ?