swollen lymph nodes are usually a sign of an infection. You say she is 11, not sure if she is developing a lot yet, though it may just be a lump from puberty. if it moves, it's probably that.
hi ive just read your articles ive suffered with the armpitts glands for 5 years on an off there really painfull an my heart goes out to anyone who has suffered them on many occasions ive been in such pain theres nothing that my docs can do except anti bo evey 6months or when they arrive, i have had one removed but the scare tissue is very sensetive an parts do break off an like me you still have little lumps under there all the time the only options left is to have my armpitts removed an skin craft means no more sweating but no more glands? when mine do come up i find that germoline,savolon,etc is very soothing and regular washing but i wouldnt recommend using sented products soap shower etc after the gland gone i do not use sented products as i find it also annoys the skin causing iching i do hope that some info can be helpful for you as am adult with the same problem but for a child to have the same problem i do feel for the little might they are so painful all the best .
I've taken my daughter several times to the doctor for the same thing but hers are on the back of her neck and just like you the doctor was not concerned because they move around or wiggle. check to see if they move if not then it might be a red flag. For the swelling they said to give her motrin
This usually is a case of an infection.