since i have no way of seeing this red bump. or examining your mother first-hand it would not be wise for me or any medical provider to blindly guess. she needs to show this skin anomaly to her medical provider or a dermatologist so that she can be properly examined and diagnosed.
my mom has a red bump on the right side of her lower abdomen area. it does not itch or hurt. . i accidentally noticed it today. she had no idea it was even there. we do not know how long she's had this.