In 3 months, my daughter will be 3. She has always loved baths and has suddenly become very frightened of them, too. She is fine taking a shower with me, but not having a bath, even if I was sitting right there with her.
Last week, she said something along the lines of "no pee pee in bath" and I realized that she is feeling the stimulation to pee because she is potty training & noticing sensations.
So, I put her on the potty & she peed. I put her back in the tub, and nothing had changed! She started crying about "no pee pee in bath" again! So, thinking that she may be afraid to pee in the tub, I told her it was okay to pee in the tub, and that everyone does it sometimes. Still, she was upset.
Thinking she didn't like the pressure on her bladder area, I let all the water out of the tub & let the water run for her to "just play." That was a tiny bit better, but didn't last for long. That made me wonder if she was feeling pressure in her colon sitting in water, and was afraid she would poop in the tub.
I learned, many years ago, that children give up their bottles & diapers when they are ready to, and that you just can't force them to potty train. They will comply when they are ready. In the process, they become more aware of sensations in their body, and they don't like the open air vs. the diaper. The diaper is what they know, so that feels natural, comfortable, even secure. Learning to relax & let their pee & poop go "in the air" is like us trying to relax & pee or poop in our underwear. It's hard, and they are only 2 or 3!! We forget how young are children really are & maybe we expect more from them than we should.
Another thing is my pediatrician told me that at this age, children become keenly aware of many things, including new sounds & new sensations. Things that didn't bother them before will suddenly scare them. They have no control over their lives, so they grab at every chance they have. It gives them a feeling of security. (Who likes to feel totally under the control of someone else?) The first things kids can control are whether or not to eat & drink, and pee & poop in the potty. We can try to make them do something & it will become a bigger battle than before. Or we can be patient and reassure them that we are there with them, and that everything is okay. We have to adjust our lives to accommodate them for a little while. That is not the same as allowing them to be in control of our homes. It is helping them.
I've seen many people raising their children through the years (I am 50) and I've never seen a child go to school with a bottle or in diapers, no matter how lenient their parents were with their training.
I hope this helps you in some way. Just know that you are not the only one trying to figure this thing out. And love and hug and cuddle your little one as much as you can. The time just flies by way too fast!