My 2 year old sons terrible cough

My 2 year old had pneumonia 3 months ago and made a full recovery after heavy duty antibiotics... a week ago he developed a cough that had him coughing about three times in a row every 4 or 5 hours. About 3 days ago he started coughing at night. He would wake up about midnight cough 3 or 4 times hard and repeat about every three hours. Last night he coughed about every 1 to 2 hours and coughed so hard he almost threw up several times. The coughing goes on for about a minute or two straight so hard he can hardly catch his breath. There is a little crackeling in the cough but more of a whishy sound like air being forced out quickly through a tube.

My older son 11 had a bad cough for about a month about 2 months ago and gave it to my middle son who is 9 and has been coughing similarly at night time mostly for the last 30 days. What concerns me is that there are no other symptoms with all three boys. No fever, no snot, no sore throat, just the severe cough that now has my two year old unable to sleep and coughing so hard he yells the cough out. What could this be??? And how do I help him??? Not even the nebulizer (were given this to help him get over pneumonia 3 months ago) works with this cough, it has no effect. I am so scared. My wife took him to the doctor this morning but I was wondering if anyone knows what this sounds like? Oh also he has been swimming in a pool we just put in for a week now. We are careful to make sure he doesn't inhale pool water and he has maybe once or twice each time we have swimmed over the last 7 days but not more than a typical toddler does when they accidently get water in their mouth and breath in at the same time. Plus the fact that this cough has worked its way through all of my children the same way makes me think it can't be the pool. So my two youngest boys are now coughing so hard it scares me. Please let me know your thoughts????

[MImom0608]

Do you have a nebulizer? If you do I would give a treatment right before bed. This helps the lungs be open at this time. If not, I would go to the doctors and see what they have to say