I've had a horrible migraine for 5 days now should i be concerned ?

Probably: If you truly have migraine, then what should be concerned about is the pain duration, as opposed to worry about neurologic complications. If you are speculating about the diagnosis or if 5 days is much longer than prior episodes, something other than migraine may be present. If it's simply a longer but otherwise usual headache, you should think about preventive therapy.

See your PCP: You should be evaluated by your physician. If you have persistant headache, it is possible to have a more serious problem such as an infection, ie: menegitis. Its always better to be on the safe side and get checked out.