I have took the sleeping pills named haclion (350mg) of two pills , and now feeling severe headache and stomach pain , does this leads to any serious problem. ?

Sounds like adverse reaction to the Halcion. Why, at age 18, are you using sleeping pills, as you can potentially disrupt your sleep patterns indefinitely? Contact your doctor and address your current challenges. Uncover the true cause of your issues, and do not focus on the secondary effects. Perhaps a valuable approach would involve a virtual consult on HT.