Cat's switching roles????

Ok so I have two cats (sisters from the same litter) who have never really had a problem with each other, until recently. Bella was the runt of the litter but was always the dominant cat and Abby put up with it even though she was bigger.
Last week I went to feed them dinner (have always eaten out of the same double sided bowl) and as soon as they started to eat Abby started to growl at Bella and would not let she near the bowl. I ended up taking the food away and putting it in to seperate bowls to feed them. I am now feeding them in seperate bowls a few feet away from each other and that seems to solve that problem. Also, they use to "take turns" playing with all of their toys, but recently that is not the case. Most toys they are ok with but the milk tabs and a certain catnip mouse have been causing problems. Abby with get a hold of one and start growling at Bella even if she isnt trying to take the toy.
They are great friends all the other times and their roles have changed with Abby now being dominant and Bella the underdog. Has that happened to anyone else????

Sounds to me like Abby has gained in confidence - they will sort out their differences and continue to be happy together

All the time. ET is one that is consistent she will growl and hiss at any and all.
The rest take turns chasing each other. One day Bailey will be the target of Lenny and Boots, the next day Boots is the target for Peak and Lenny, two hours later it could be Peak as the target for Princess and boots. Bart and Mits are never a target except for ET.
We never know who is going after whom. We have water swart bottles all over the house. If it sounds like it's getting too rough someone gets wet. ET seems to have a tendency to attract a water.