I have EIA and a problem......?

I have EIA which is exercise induced asthma. It has only shown up as I have progressed in sports in high school and have had it (diagnosed) for two years now (I am 20). The problem is, is that I cannot run for longer than 5 min at a time due to I get a very congested feeling in my throat and chest like i need to spit up flem but I cant and this hinders me from running distance. My problem is I am testing for EM PA a police academy in MO in 8 weeks and I have been trying to run the 1.5 mile (IN 14 MIN) but cant do it without stopping multiple times due to the above symptoms. Has anyone else had this issue and what has helped you. I am desperate.