In early Alzheimer's, your mother may have both good days when she seems like her old self, and bad days when she's very forgetful or confused. As professionals, we don't
always know the reasons why. Everybody with Alzheimer's is different. It could be partly because of a medication, but typically, it's the stress of "newness."
As long as your mother is doing things that are familiar to her, following a routine, and being with familiar people in familiar surroundings, she may do much better than in new situations. These could include new restaurants, new people, or new activities, such as a vacation or visiting a new doctor in an unfamiliar building. In those new situations, the symptoms become more obvious.
Sometimes when she's doing well, it can lead you to overestimating her actual abilities. I often hear something like, "Mom seemed to be doing fine with her assisted living, so we decided she should go back to see her distant relatives in Germany." Then later the child or spouse reports, "She was so confused on the plane, she didn't know what to do at the hotel.…" New and different circumstances can throw off someone with Alzheimer's.
If your mom is put in a new situation, be prepared to see her confusion increase; she may not be able to function at her usual level. Of course you can't avoid all novelty. Some new experiences, like going to the doctor, are valuable and necessary. But even at a familiar doctor's office, there are many nurses and other physicians. She may seem fine until she gets there. At those times, be prepared to offer more guidance and more support.