What Are The Side Effects Of Loestrin Pills?

Hi i started taking loestrin 24 last month, i didn't have any symptoms the first pack that i took but as soon as i took the second pack i've been getting stomach pains and excessive burping. it stops in the morning but as soon as i take the pill (almost exactly the same time at 10am) the symptoms come right back. I'm starting to get worried about pregnancy because my period this time was only 2 days when i used to have up to 7 day periods.