Suddenly agressive Ball Python, needing suggestions

[Jeanie78]

Hi! Hoping to get some ideas and hopefully answers about our ball python, Spike. She is about 6 years old, we've had her for 3 years. She is about 4.5 feet long, and fairly normal in size. She has always been very gentle, timid, healthy and eating well. When we first got her, the previous owner was feeding her live mice, in a separate container, and since we've had her, she has graduated to a small rat. We have always fed her live rats, and in a separate container, since we were told that it was best to feed her out of the terrarium. We have tried a couple of times to feed her frozen (thawed) rats, but she refuses to feed when we do that. I am aware that feeding live is not great, for obvious safety reasons, so when we do feed, we monitor her very closely to make sure that she is safe, and eating well. We then transfer her gently back to her terrarium after about an hour.
She lives in a corner of our kitchen in a 45 gallon terrarium. She has a ceramic cave that she loves to hide in, a branch to climb on, and a fairly large water tub that she will drink from and slither through.

Here's our situation: We fed her a small rat on Wednesday, and Friday, she was already back out of her cave, "hunting" again, and seemed agitated. Saturday, she had her whole body in her tub for several hours, and when I walked closer to her, she struck at the glass. She had never done that before. After researching online, my husband and I decided to see if she was hungry and fed her another small rat, even though it wasn't her normal feeding day. She ate the rat very quickly, and when we put her back in her tank, she went in her cave, and has been calm since.

My question is, does she need to graduate to a medium rat? Does she need to feed more often? I would like to keep her feedings to around every 10-14 days, but I also don't want her to be so hungry and agitated that we can't handle her without being bit. I would also like to start feeding her frozen rats, but I'm not sure how to go about that. She has so far refused the frozen, but I wonder if it would be different if we fed her in her terrarium and not in the separate container, if she associates that with live rats.

I hope some of you can give me some suggestions, and if you would like more information, please let me know. I really appreciate it.

I don't claim to be an expert on snakes, and a lot of the ways we do things with Spike is with advice from the previous owner, and whatever advice we've picked up along the way.
Thanks so much!