Where to find resources to help handle dealing with my Mom's mind slipping?

Mom was recently put on a low dose of anxiety meds (Lexapro?) after a bad bout with pneumonia and boy did it work great! She is fully recovered now, but her and I are both noticing changes in her behavior. She isn't reasoning well, communicating well or understanding things like she did. We have a call in to the Dr about it and have chosen to cut the dose in half per the recommendation of our pharmacist.

My question is this, situations arise either in conversation, or every day living where she doesn't reason something right and argues with me, or says things inappropriate to the conversation. This irritates me which makes me feel a-w-f-u-l, but it's new behavior from her and I'm trying to remember that. Like this morning she asked for waffles and an egg for breakfast. I always ask her what she would like to eat. I said that I only had gluten free waffles left and she said ok. I fixed her a plate then went outside to water my little garden. While I was gone my daughter come to the kitchen to eat and mom said to her, "Why does your mother give me these old waffles? She knows I don't like gluten free waffles." The problem is that she liked them a couple of days ago. Sunday we were sitting in the fellowship hall of church eating dinner when she leaned over to me and said, "Why can't people remember what I like and what I don't?" She was very soft spoken and sincere, she did not mean any harm, she just couldn't understand why people can't remember that she doesn't like smoked meat. It flew all over me! As if the whole church needs to remember what she likes. Of course I felt like a dog for thinking what I did. It's these kinds of incidences where I need to stop and realize she's not herself. I need help knowing how to handle these times. Some say never argue or correct. Some say gently correct. What's sad is that she realizes she's doing these things and feels bad, she feels like she's "slipping" as she calls it. I feel the anxiety med is partially to blame, but she is 88. I don't want her totally off it because it is helping her sleep, but she is imagining things, like that my husband hates her walker.? I guess one time he moved it out of the way and it rolled off the little step in the living room and she was convinced he slung it because eh hates it. Of course he laughed when I told him. He went into her room and told her that he doesn't even think about her walker, that it's perfectly ok with him that her walker is here. Then she was convinced that my daughter is sad because she ate her gluten free waffle this morning.? After the waffle incident I explained to her that I told her that was the only kind of waffles I had and that my daughter doesn't care that she eats whatever she wants. I told her she wasn't acting herself and she's been depressed ever since. I need help handling things right. I don't want to make her suffer emotionally by reacting incorrectly when she can't help it. She has been a precious momma and so easy to live with, but I fear the road is going to be bumpy if I don't learn what and what not to say/react/do. I see her going down quickly. I really wish she had a geriatric Dr., maybe they would be of more help to us.

Thank you so much for a place I can come to get advice.