I Have Been Having A Sour Taste In My Mouth

I have been having a sour taste in my mouth can that be due to allergies or due to to much of allergy medicine like a bendryl???? I felt Dizzy and I Almost Fainted but I have been feeling better that was a few days ago and My Stomach felt like I was going to throw-up to but those syptoms disappeared as well, but I still have the sour taste in my mouth and I had a post nasal drip as well.... Thanks,