Thanks for your qGERDion on HCM. In my opinion you are having GERD (gastroesophageal reflux disease) mostly. And no need to worry for pregnancy due to unprotected sex because your timing of sex is in non fertile period (just after menstrual bleeding). But get done urinary pregnancy test to rule out pregnancy. Better to avoid such unprotected sex. Use condom. And your current symptoms like central chest pain above abdomen is mostly due to GERD. It is because of laxity of gastroesophageal sphincter. Due to this the acid of the stomach tends to come up in the esophagus and cause the symptoms like burning central chest pain. So avoid hot and spicy food, avoid stress and anxiety. Start proton pump inhibitor.