I Think I Got Bit By A Spider About 4

I think I got bit by a spider about 4 days ago. The bump started out as a nickle sized red bump with a needle poke sized black dot in the center. I left it alone and didn't do anything that night. The next day the bump had turned into a goofball sized red bump and the black dot was still there. I put a mix of baking soda and water on the area and it helped with the swelling and redness. I also put on some knock off neosporin cream on it after that. The bump was still red and still there the next day. I put more of that baking soda and water mixture on over night and now the bump is back to nickle sized and it's purple. Put more mixture on again that night and it's still the same. The black dot is there and the bump is a dark purple. Any ideas???