I'm taking amoxicilin, omeprazole, azithromycine, bismuth subcitrate. can i have constipation in first days and now have diarrhea?

Yes: Bismuth can cause constipation but antibiotics like amoxicillin & azithromycin often cause diarrhea because they kill much of our friendly flora as well as unfriendly bacteria like H. pylori. I advise all my patients to take probiotics like Sacchromyces bouardii & lactobacillus acidophilus & bifidus while taking antibiotics & for a few weeks after to prevent & reverse diarrhea from antibiotics.