How hard is it to get a medical Wavier?

How hard would it be to get a medical Wavier for USMC or US Army? I had Henoch–Schönlein purpura when I was 11, I'm now 18 and have had nothing since and am in great health. But it's a disqualifying medical problem ongoing or History. Ive been discharged from hospital and don't have to go to the doctors or anything.