Apple ID keeps getting locked for "Security Reasons"

Hi Everyone,

So my apple ID keeps getting locked month after month for "Security reasons". Now my ID is shared between 3 apple devices, all of which ONLY USE IT TO UPDATE APPs. I mean no downloading of apps, nothing. This used to happen waay back before too but then I changed my password and security questions etc and it got fixed.

Now, about a monthish back, I, for the first time, loaded a tiny amount of money to my ID to make an in App purchase. the App was Clash of Clans by supercell, so its pretty much a trusted app. But ever since I did this, my ID has been locked thrice.

Any help would be appreciated. each time I changed my passsword too but this is just becoming a nuisance.