Brown recluse spider bite. How can you tell you have one?

Brown recluse bite. Severe symptoms include blistering (common), necrosis (death) of skin and subcutaneous fat (less common), and severe destructive necrotic lesions with deep wide borders (rare). Minor symptoms include severe pain of bite site after 4 hours, severe itching, nausea, vomiting, fever, and myalgias (muscle pain).
Best to see a doc. Recluse bites typically have an ulcerated center with a purple halo. They can be toxic to the surrounding skin so if there is a question go see your doctor.