Running weak

I haven't run in about a month or so.  Found out what is causing the trouble.  I have a hyperthyroid (graves disease).  It speeds everything up.  So if I were to run my heart my go crazy and actually stop.  I finally am on medication and feel a lot better, but I am still weak.

Looks like I'll need to step down to a half marathon in St. Louis instead of a full marathon.  I'll have to start training all over again.  I just want to do it.  No worry about time.