Are you sure it was a Brown Recluse? Have you seen a doctor? Where were you bit? BR bites can cause large patches of necrosis which develop the weeks following being bitten, and can lead to the loss of a limb or large patch of flesh. What may seem like a small red spot may soon develop into a large area or necrosis (dead tissue).
Search "brown recluse bite" on the web and you'll see very graphic photos of recluse bites of what I'm talking about.