My dad had a spider bite that got increasingly larger at the site. Swollen,,,painful. Not really much redness, no fever/chills. Went to the dr. They prescribed Keflex for the localized infection, cause he is diabetic. That was on the third day after the bite. He started taking it on the 13th. The last two days he has been having difficulty catching his breath. He also had a pace maker put in last year, cause his heart wasnt beating fast enough and would quit for up to 17 seconds at a time. He has had previous heart bypass surgery. Before the heart surgery, he would get short of breath. afterwards, was immediate improvement with that. Wondering if there may be a reaction to the Keflex or maybe something more to do with the heart. Checked his pulse last night and it was 60.