Hi. i thought i was bitten by a mosquito yesterday but a bigger red spot with a run has developed so it may be a spider bite. how should i treat it?

Skin redness extending outward from any insect bite, especially those with red lines, should be treated by a Dr as Cellulitis. You will need prescription antibiotics, and a visit to the Dr for follow up. If you are hesitant about going to an urgent care, a Telemedicine Physician can examine the area on video and send the prescription to your Pharmacy.