Lost potion of life on nightmare

So during act 3 I completed the first quest and was not given the potion of life reward. Realized I had the normal difficulty one in my stash for some reason and switched to normal and used it. Now the nightmare one is just missing. I tried talking to Alkor and replaying the quest dialogue but no luck. Anyone know how I can fix this by chance? It’s an online character I’ve sunk about 30 hours into.