Pollen allergies symptoms and conditions

I took Zyrtec for a few years for severe mold and pollen allergies. I loved the drug as it controlled my allergies much better than Allegra or Claritin. However, I recently stopped taking it after realizing it was causing dizzy spells, drowsiness/constant tiredness and heart flutters. Since I stopped taking it I have lost 6 pounds without making any alterations to my diet and exercising less than normal. This leads me to believe that my weight gain of 30 pounds in the last few years was also part of zyrtec's side effects.