Irregular heart rhythm on fitbit. Is?

Hey docs,been noticing this from last few weeks I might just ask about it.So before I say anything I have had all heart tests 5 months all clear.i am noticing some strange heart rhythm on my Fitbit nowadays I have attached screenshots and marked them.Can someone explain what this is?and btw I get premature contractions a lot sometimes multiple in a row sometimes they are really strong and my other symptoms are:Sharp pains in chest lasting for few seconds,mild shortness of breath(anxiety), shooting pain only as a flash on either arms or shoulders but not always..What I think is my pvcs or pacs have actually weakened my heart as the my rhythm is getting progressively worse from last 5 months since it started..I get butterflies in my stomach all the time which messes my heart rhythm I have seen it on fitbit..no loose bands the reports are 100% accurate..I am 17 pls help