Abdominal Pain and Lower Back Ache

I am 18 years old and for a couple weeks now i have been experiencing tolerable to agonizing sharp pains in my lower abdomen. I have already been to the doctor who diagnosed me with Irritable Bowel Syndrome. However, he did not preform any tests, he just gave me a diagnosis based on my age. He recommended that i eat more fiber and sent me away with some meds. The meds did not help so i booked another appointment and he told me the same thing and changed my medication. Since the second visit to the doctor, the pain has moved to my ribcage, stomach and lower, lower abdomen.. it is still persistent and sharp and tends to worsen when i engage in physical activity.
I am really starting to get scared and do not know what to do. I am currently in South Africa on holiday with my parents and can't see a different doctor until i return to New York.
Please give me some feedback