Freaking out over abdominal pain??

Hello I am 17 years old and have had this symptoms for nearly a year I would say and started suddenly out of nowhere during a bad time in my life last year around May or April.

So I had this dull pressure under my lower ribs on my left side and it never bothered me, I still ran and did things normally, my only issue was when I laid on my stomach at night i felt that pressure and usually shifted to the side. It was soo odd but for some stupid reason I never cared to go to my gp to take a look. It doesnt stick out it is not bruised. Nothing is swollen and i dont think it gets better/worse with food.

Im freaking out now thinking the worse. These last few days its kind of been more prominent. I keep thinking I have cancer or a tumor. Ive looked up some stuff and and some things like enlarged spleen has popped up but I dont thik i have an infection I cannot find a reason for it other than a tumor because it just feels like a pressure. Tomorrow I am finally going to build up the courage and tell my mom.

Has anyone experienced this and gotten answers or a diagnosis? Thank you all. I will update you guys on my status soon

Pressure can also be build up with gas that can be due to IBS or disturbance of gut bacteria 

Is your diet healthy or have lot of junk food? 

Try a good probiotic drink.

If your symptoms came on during a stressful period in your life, it could be IBS.  After I had several months of stress, stomach pain started which was eventually diagnosed as IBS.  It came on very suddenly.  One day I was fine but the next morning I woke with stomach pain that never went away.  Do you have change of bowel habit?

Could it be gallbladder?

I have the same thing a dull mild pain on my left side same line of my belly button for a year off and on I'm 47 female. Now the last 4 days I have been nauseated in the morning. In nov 2015 I havdb MRI of my abdomen and nothing everything is good. I have a sliding hiatal hernia and inflammation in the small intestine and the duodenum. Did you go to the doctor? I'm concern too