This is something I feel you should definitly pursue. I began having strange symptoms at the age of 16 and still continuing to progress and worsen now at age of 19. These symptoms include in order:
-chest pain left side
-chest pain low left ribs
-loss of breath completely during exercise
-decreased energy
-extreme lethargicness/fatigue
-feeling slightly nauscious
-having to pee frequently and many times throughout the day
-feeling full quickly even if still feeling hungry
-bowl habits loose and unpredictable all of the time
-severe menstrual cramping (began period at age 11, starting cramping age 1
-cycle becomes irregular
-stomach bloating and fullness worsens
I danced for 14 years, always have been on the skinnier side - genetic and due to exercise i suppose, doctors assumed these were due to eating disorders, or even pulled muscles
The fact is that these symptoms are often overlooked and need to be tested and payed cloes attention to whether for a peice of mind or to get a proper diagnosis
About 6 months ago I had an ultrasound that found I did have endometriosis but this was entirely overlooked by both my mom and doctor, after meeting someone who went through a similar experience a while back, found she had actual masses of cysts growing that became a hormonal problem which caused these symptoms. Seeing an Endocrinologist or gynocologist and informing them of your symptoms will help you reach a precise diagnosis - both of which I am finally on the path of doing thanks to this person that I met.
I have had many family members as well that have died, or come close to with colon cancer, ovarian cancer, and lung cancer. This family history can be frightening and need to be taken seriously.
Please look further into the situation, your life is much more important than the money, I hope that my own current experience can help motivate you to take yours more seriously, your friend is trying to help you!
Wish you luck - from someone who truely understands.