Struggerling with Peak Flows

My son John is 10 years old.... He is on Omalizumab , Seritide, Salmeterol, Salbutamol, Montelukast, Slo-phyllin, Lozec and 8 x 5mg prednisolone and has just been weened off a 24hr subcutaneous infusion of Terbutaline..... I am at present struggerling to keep his peak flows above 190 - 200 after salbutamol, without salbutamol he is getting 170 and struggerling....... John is on maximum dosages of his medication and I am getting really worried that there will become a time that if his peak flows drop further, are we going to be able to get him pulled around... We see the consultant every week at the moment but since we have taken his infusion away he is now waking every night coughing and generally feels awful... We obviously dont want to go back onto the infusion as for a boy aged 10 it is something that makes him different from the rest and this is not nice for him... Can anyone suggest anything else that I can do..... I am really desperate....

Beverley.