3 Unknown Type Of Spider Bites On Thurs Evening After

3 Unknown type of spider bites on thurs evening after moving bricks in the yard. Red Infected bite sights are ranging in size from silver dollar to the size of my Palm. Sought urgent care treatment next morning. Antibiotic shot was administered along with prescriptions for tetracycline, Bactrim, claritin, benidryll and Motrin. I traced the sights with marker to see if they grew. Two shrunk and 1 grew outside the lines. It's been about 36 hours now and I'm feeling weak with mild stomach cramping. Is this medication side effect or do I need to seek medical treatment?