Cats attacking kitten suddenly?

I rescued a kitten almost a year ago, and the cats i already had were fine with her until about 4 months ago. Out of nowhere 2 of my adult females started being very aggressive with her. It started with one, then the other joined in, My kitten can no longer get out to eat safely, unless i bring her to the food, and keep the 2 attackers away from her...though they seem to be leaving her alone for bathroom trips, as I've found no evidence to suggest otherwise.

My one cat is very territorial, and i think that's one of the reasons that she's attacking, because i carry the kitten around and snuggle her to let her know she's safe, but I give the territorial one PLENTY of love too...she doesn't attack my other cats when they snuggle.

Also, the kitten is not spayed yet..and yes, i know I'll catch flack for that, and i know it should be done. But could that be relevant to the attacking? The other 2 females ARE spayed.

I'm at my wits end, I don't know what else to do to get the attacking stopped, I've tried everything I know. I'm at the point where I think re-homing the kitten is the only option left.