those poor horses and other warm blooded mammals

something bit me recently on the sole of my foot.  i woke up with a very sore foot and there is a hard and extremely painful lump beneath the ball of my foot about the size of a small marble.  the next night i was getting into bed when i noticed a march/horse fly on my bedside lamp.  i didn't know that they bite but it is the most plausible reason.  i sprayed the house liberally and went outside but haven't noticed the corpse anywhere so i hope it's dead.  my dil told me she is allergic to them.  i showed my foot to the doctor the other day when i went in for something else but she showed little interest in it so i rang the podiatrist.  he's going to look at it tomorrow for me.  maybe lance it if necessary.  apparently they have serrated jaws and can tear flesh.  it's not red or itchy which baffles me.  maybe it's something else entirely.  let's hope Paul can help.