If this were a bite from a deadly spider he should have been buried a few weeks ago.
Sorry, but this is just not a spider bite. A common spider bite would be healed or nearly so by now, and a dangerous spider would have hospitalized you in 3 hours, not 3 days.
Your brothers injury was not a bite either if it is similar.
These are skin infections and not related to spider bites. A genuine spider bite will quit hurting within a couple hours, except a black widow bite.
On very rare occasion, these infections can become so severe as to need treatment, but usually they heal nicely on their own. They respond to heat, such as soaking in hot water or hot towel. Often they may come to a head, like a bad pimple and rupture draining the pustule. In this event, a topical antibiotic should be used.
Many people that have never been bitten by a spider, mistake these abscesses for bites, because they don't know the difference, and with genuine spider bites, the culprit spider is usually caught in the act.
I might also point out antibiotics are not prescribed for these bites.
For common bites, just wash with soap and water and go on your way. The exception is if there is an allergic reaction such as swelling about the face or mouth.
For dangerous bites, Have them examined by a doctor, this will determine 'IF' treatment is needed.
You will need the culprit spider for identification as well.
Harmless spiders are called harmless because they cause no significant injury, hardly more than just another bug bite.
In your case, if your injury seems severe or worsening symptoms, you should have it examined by a doctor. It may have to be lanced and drained surgically.
PS: @ Lauryn, no one has ever lost a limb or appendage from any spider envenomation, and no PHd would even suggest such a thing.
Been there, and been around spiders 50 years
UC Irvine, entomology