urgent advice needed chester

Hi Really need some advice. I've chester marathon in under 4 hours!! Full of a cold, what do I do? I know all this about if above the neck blah blah blah. .. however I suffer from asthma and am worried something will happen. Went docs on Friday told its viral and to run at mt own peril, can lead to cardiac infection. Don't feel 100%, but with a push could probably run. Husband does not want me to do. Also If I were to do liverpool nxt week instead, does it matter that last LR was 3 weeks ago?. Thank you toni xx