Your child is suffering from mild, intermittent asthma. Such children generally improve in due course and they often become free from the disorder. This is already happening to your child.
The treatment of mild, intermittent asthma in children (5-12 years) is internationally codified based on evidence-based medicine. Such children should be given only either short-acting salbutamol (such as Derihaler-100 or Asthalin Inhaler) 3-4 times daily or long-acting salmeterol (such as Salmeter or Serobid) 2 times daily.
If the response is not adequate i.e. the patient requires more than 10-12 puffs every day, it becomes necessary to add a steroid such as fluticasone.
I hope your child is not taking both i.e. Derihaler and Forair because both contain similar medicine i.e. salbutamol in Derihaler and salmeterol (along with fluticasone) in Forair. Salbutamol and salmeterol both belong to the same group called B-2 agonists. We do not give them at the same time.
In conclusion: if the child is responding well to salbutamol alone (i.e. Derihaler), then there is no need to add a 2nd medicine. However if the control is inadequate needing more than 10-12 puffs a day, then a steroid needs to be added. In that event, Derihaler should be discontinued and replaced with a combination product such as Forair.