Insect bite with bruising?

my brother had those same symptoms.he was bit by a brown reclus.you have to have shots with in 48 hours.it could rot,or have to be amputated. he didn't see a bite mark either and it really started hurting.if the bite is by the brown reclus and near a blood vein the poison could enter the blood stream and well it's bad now but it could mean his life.the doc.told my brother he was very lucky he came in in time.i hope you make the right decision for him and knock him in the head and take him to doc.lol.really though this is nothing to play with.