Your daughter has an allergic diathesis ie she is prone to develop allergy
to various allergen and that`s how she has been diagnosed asthma
in the past. Similarly when she enters the pool,she is reacting to various allergens that may be present in the pool including the chlorine and the cold
water. You must ensure that the [pool she is using has good standard of hygiene and is cleaned regularly. You may try putting her on some inhalers like aerocort or seroflo
and a tablet of monteleukast for 3 to 5 days and then take her to the pool. These medicines can be continued for few days to weeks as these are very safe.