I recently went to Mexico and forgot my birth control. I have been on Chateal for about 6 months now. However when I left for vacation I forgot to pack it. I was on my Sunday pill of the first week (I was finishing up my first week of pills of that pack. I did not want to have my period on vacation or have to stop talking the pills so I went to a pharmacy and got the closest match - same mg of ingredients (LEVONORGESTREL 0.15mg, ETHINYL ESTRADIOL 0.03mg) but not the same brand. after taking the mexico pill for a week and 2 days I am having side effects that are not fun for me - or my partner. Can I just switch back to my usual pills - Chateal? without having to finish the Mexico pack? If I can, do I need to start a new pack of pills or just go to whatever day I am at now and the pill pack and start there?