Have you seen a pulmonologist or allergist?  It's a good first step, because
they are much better at diagnosing and treating respiratory problems than
general practicioners.  It is possible that opportunistic bacterial
infections occur because of his weakened state during and after a cold.
This of course, can require antibiotics to resolve.

An allergist will  try to identify any allergens--including contact,
airborne and food--that could be triggering attacts.  Sometimes elimination
diets are tried, in order to identify potential food allergies.

If a doctor has prescribed a rescue inhaler (albuterol), and you feel as if
your child is in trouble, then of course it should be administered according
to your doctor's advice.  If the inhaler is still not bringing relief after
twenty minutes, or his condition is deteriorating rapidly, then a trip to
the ER will be needed.

The best thing that you can do is to work with your doctor to formulate an
"action plan" that spells out checkpoints and reactions to your child's
condition.  This will define what is serious and what is not, so that you
have a good feel for what is going on, and if it's time to go to the ER.

I wouldn't just administer ibuprofen automatically--a moderate fever can be
beneficial in the body's fight against infection.

Good luck.