For A Week Now, My 18 Year Old Daughter Has

For a week now, my 18 year old daughter has been having stomach pain. she can barely eat or sleep. she has taken zantac and anti-gas medicine with little to no relief. she says its hard to swallow food and feels like she is going to puke but has not yet. no fever. she has missed 4 days of school and 2 days of work which is not like her. she is very pale and stomach is very tender. has had small bowel movements. she also just mentioned to me that the last couple times she had sex, it hurt. Any ideas?