Hi Mila,
Sounds you're scared...that emotion is feeding all the physical symptoms you're experiencing. When this first hit me I felt exactly the same way you're feeling now (I don't have asthma) - tight chest, can't breath, shaky, tight throat, can't swallow, dry mouth, achy head, the runs, thinking about it ALL the time - you name, I had it. Best advice is what others have said, distract yourself with something physical that also requires some degree of concentration (aerobics video, sing and vacuum?), get some deep breathing going and reassure yourself that you're ok. You are ok! The doctors have said so too.
Take care,
Sue