Hi and welcome to Just answer.
Is your dog up to date with heart worm medication?
Has the dog been around other dogs?
Does the dog have a temperature if so what is it?
when was the last vet check up?
Does it sound like its gagging or choking on something then it stops? Does it come on randomly?
Thank you for that information. If she is not on a heartworm preventitive I would be concerned with that. You will notice a cough with heartworm. A heart problem given her age is another concern.
Wheezing can be a sign of respiratory distress as you said but this would need to be treated with antibiotics if it is a bacterial infection.
You mention she got sick one evening. Is she still eating and drinking normally?
does she ever eat bones or other non food items like rawhides, pig ears etc.?
I am also thinking of a reverse sneeze as that sounds and looks like the dog is choking on something and I will direct you to a site which has a video. They don't all sound the same, some are worse, some not so bad, but you'll get the general idea. http://www.petplace.com/dogs/reverse-sneezing-in-dogs/page1.aspx
Kennel cough gives a dry honking cough or gagging effect as well. http://www.petplace.com/dogs/infectious-tracheobronchitis-kennel-cough/page1.aspx
Wheezing can be a sign that she inhaled or possibly aspirated on something which could be what happened when she vomited. Check the gums if they are gray or bluish she is not getting enough air
Wheezing would indicate possible infection and I am worried that she does need to be seen. Anything that interferes with breathing should be looked at. There could also be a collapsed trachea type thing going on or some type of pressure on the lungs, with an older dog tumors are always a worry as are heart problems. A tracheal collapse could show trouble with eating, but the wheezing is the most bothersome.
If she activly hunts then she may have a foreign object that made its way past the windpipe and that is causing a problem .
Here is more on a collapsed trachea. Symptoms and treatments
I have to be honest here, I think this warrents a vet visit. I can direct you to sites that may be able to help you with payment or you can call your local pound as they may be able to refer you to a vet who works on a sliding scale, that can work with payments.
for help with payment