My son has episodes where his lips turn purple and he feels extremely hot... I NEED HELP!

My son Alex is 7 and has had a few episodes where his lips will turn purple, he is very pale and he starts crying because he says his body feels like he is on fire!  We took him to the Emergency room about a month ago and they did all kinds of tests and said he has asthma.  Well, i thought this was great!  BUT, I am not convinced.  He has had another episode and his enhaler did nothing for him.  No doctor will listen to me.  What is wrong with my son?  I am scared to death!  Please help!!!!!