Ok, who told you not to nurse her? The doctor? Is it because she will throw-up every time?
Ok,first of all ,I am not a doctor but a mom of three 6 and under who has been nursing non stop since my first was born . I am still nursing my 17 months old and did tandem nurse the first two for a year. So, i have A LOT of experience with nursing through sicknesses (since i never stop nursing since my first one was born)and even surgery(my last one got heart surgery at 7 months).So, here is for you what i will do if she were mine:
Nurse her as long as she will take it .Why nurse? Even if she throw up half of it,at least she got something in which will help with the dehydration .It is what your guys are used to do.So it is comforting to you both and this is good while she sick. She does get the nourishment and immune benefit of nursing even at 11 months old. And she needs even more immune protection when she is sick.My first two used to nurse every 2/3 hours when they were sick.It was just like having newborns again for 5/7 days and then they were fine until the next sicknesses (sigh) . However ,my last one was not so good at nursing a lot through sicknesses .As a result (i think) ,it always takes him a lot longer to recover from sicknesses .It could be his heart problems too though.
Over the summer, he got Roseola and totally refuse to eat or drink anything at all . We even try formula then as he was refusing milk ,pumped breastmilk ,my boob, juice .... nothing worked. So we took him back to the doctor very worried. The doctor said that he was mildly dehydrated and gave us the choice to hospitalised him for I.V. or try to syringe feeding him liquid(pumped breastmilk mostly and some formula) over the weekend. It was A VERY HARD weekend .We were feeding him 10 ml of liquid every hour or so per syringe as this is all it will take. By monday, we went back to the doctor . He was still dehydrated but much better and started taking sippy and breast again and was on his way to recovery.
So, here this my experience with nursing through sicknesses .Hope some of this help.
Good luck and hang in there.Just offer her liquid often and the dehydration should get better.However if you still worry about her being dehydrated ,don't hesitate to take her back.Better safe than sorry.And remember you are the mom and mom have usually good instinct .So, trust your and good luck. :-)
N..