Can a personal doctor help me avoid having to get a waiver after making a stupid mistake at MEPS?

I went to MEPS to rejoin the military, specifically the Army Reserve. While I was there, I was talking to the doc and he asked me if I was allergic to anything. I said that Robitussin makes my stomach hurt. He said how and I explained that I took Robitussin once and it made my stomach hurt really bad. He went ahead and listed it as an allergy thus not allowing me to be medically cleared. My recruiter gave me the bad news after all was said and done, so I texted my Primary Care doc and he told me that what I was experienced was not an allergic reaction but only a side effect to the medication. Now I have to wait for waivers, but I was wondering if I got a note from my doc stating that it is not an allergic reaction but only a side effect I experienced once would that allow me to bypass the waiver process or would I still have to get the waiver?