Worried about allergic insect stings

I was bitten by something last week.  When I woke up, I noticed the red wheal common to an insect bite.  Within hours, however, it had formed a large blister on the site.  It swelled and bruised around the sting as well.  The bruise was very dark purple in color and about 6 inches in length and 2 in width with the sting in the center.  (I was visiting at my Mom's.)  Since then, both my mother and my sister (also visiting) have received insect bites with similar bruising and blisters.  We've all had mosquito bites, but I think this is probably something else.  They've killed about 4 brown recluses in the house, but not sure if that's what this is.  Does anyone have an idea what causes a bite like this?