I am sorry for the delay, but I temporarily lost internet connection.
Since it has been 3 days since this started, it is not typical for a poisonous spider bite. In the US, there are only two poisonous spiders, and only one of those has a local poison that will cause a reaction in the skin - the brown recluse spider. The venom of a brown recluse spider bite will cause rapid death of the tissue of the skin, usually in the center of the area of redness and by 3 days, it would typically be much more advanced than it appears in this picture.
There are many other spiders that may bite humans, and humans can be sensitive/allergic to these other spider bites, but these other spider bite would be similar to sensitivity/allergy to any bug bite.
The reaction in the pictures, then, could be a reaction to a generic spider or to any insect bite. There are several interventions that can be done to help these areas heal. It can help to take an oral antihistamine to limit the sensitivity/allergy. It is important to be cleaning the areas a couple times each day. An over the counter hydrocortisone cream can then be applied to help ease the inflammation in the skin.
If I can provide any additional information, please let me know.