What To Do For The Tender And Red Area In The Thigh?

my dad has tender, red, area on inside left thigh, doesnt remember injuring area. Was placed on antibiotic- with slight improvment.Has had blood work, culture done came back idiopathic. Now he scheduled for MRI in 5 days but his next appt is 8 days later. Has been going on since July10, now end of July. Just concerned Drs not acting quickly enough. What should he or I do ( acting as his health advocate)?