[Gameplay] Random LP Decay and Demotion

So I just finished a ranked game to find I have been demoted to silver 5 due to inactivity and I am still experiencing LP decay. I had played anther ranked game just a week ago and I should not be having that problem. I did not lose 3 games at 0 LP so I shouldn't be demoted from losing either. I would appreciate any help on the matter as it would be ideal not having to deal with silver 5 again. Thanks