Hello, As you are on the birth control pill for last 15 years, chances are very rare that you may get pregnant. So stop worrying about it. Also, you lost your virginity last week only so you must have broke the hymen. That may cause abdominal cramping. The reason of nausea and vomiting could be your anxiety and excessive worries about gettig pregnant. Stop worrying too much and try to relax. In case you are delayed for your periods, it could be because of stress. Stress causes release of stress hormones that can cause disturbance in hormonal levels and irregular cycles. Still, if you need to confirm, you can take a home pregnancy test available over the counter and get the results after peeing on the stick. The instructions are nicely given on the packs. However, I am suspecting food poisoning a reason for your stomach upsets and symptoms. It might be just a co-incidence that your symptoms started after having sex. I recommend you start an antibiotic course to get stomach infection under control. If you are not allergic to Norfloxacin, start Norfloxacin (Norflox) 400 mg two times a day for 5 days. You can have pain relief by taking Paracetamol (Crocin) 500 mg twice a day till you need them. Drink lots of fluid and restrict on heavy diet. If the symptoms do not come under control in two days, I advise you to see a physician for physical examination. Do complete the antibiotic course even if you find relief from symptoms. I hope this information helps. Thank you for choosing HealthCareMagic. Take care. Best, Dr. Viraj Shah