Milk allergy is causing asthma/severe coughing in toddler. what can be done to treat this?

See doctor: If indeed this is an allergic reaction, seek medical help immediately.

Avoidance: Avoidance is key. If your child is already having symptoms of cough and nasal congestion, you can give an antihistamine: benadryl, (diphenhydramine) Cetirizine or loratidine at the right dose (check w/ doctor). If your child is having shortness of breath and wheezing, you will need a breathing treatment which can be prescribed by your doctor. If you need to confirm allergy see an allergist for testing.