So i bought a "Sasha" about 18 month ago, shes a nice loving dog.. She plays with me my sis and mum, i would say I'm the one that is strict with her. But lately after no trouble at all shes starting snapping at my mum and sister, now ill be honest shes a staffy cross, lovely dog, since i got her me and my mum have been working loads she only gets out when its possible for us to take her out, so.. She sometime stays with my sister on her bed, but not all nights, but tonight was different she actually bit her after my sister kicking her off her bed, not hard, just left a slight mark, but shes also snapped at my mum like this a couple times in the car, because my mum was telling her off for barking at another dog.. But this has only started last few days and the difference is shes hasn't done it with me at all, like if i ask her to go downstairs she does straight away no problems but when my sister tells her she snarls at her?. I don't know if this matter but ill mention it non the less, she spins after her tail in the garden, but for like 20 mins solid, and after she gets it she holds it like a dummy, later on she will start to lick her leg! But again the spinning has been from day 1, licking her leg.. Last couple weeks. If my mum or sister takes her to the shop she wines outside and acts up, me? Shes fine with and behaves well, same with other dogs, mum and sister walk her shes aggressive to them, i take her.. And shes fine! So I'm really at my wits end now, because its putting a strain n the family.. Because if she attacks someone properly, i will have her put down. So can somebody please help me! Tell me what im doing wrong.