I was in my teens when I had similar symptoms, but my GP suggested doing a Food diary, for 3 months, writing everything down that I eat and drink, and what symptoms I get after it, ie. cramps, diarrohea, nausea, pain, etc,
I did this, and went to my GP and he was surprised that certain foods that I have eaten for some years, are now having an affect on me, He then referred me to a Food Intolerance Consultant, who then tested a load of foods on my arm, and monitored the reaction, we came to the conclusion that I was lactose intolerant and protein intolerant, (basically dairy products had an effect on my bowel and Gut).
I was then referred to a Bowel Specialist who performed some (not so pleasant), tests, ie, scopes up the rectum,biopsy of the bowel, barium enema, etc, and gave me diagnosis of Irritable Bowel Syndrome.
Put me on a specific diet, high fibre etc, and gave me Peppermint capsules, and bowel tablet, (Loperamide (immodium), a muscle spasm relaxant (colofac), and I have managed to live with the condition now for 30 years,
There is obviously changes in the tests, and treatments to what I have had 30 years ago, but some of the treatments are the same.
I would suggest you keep a Food and Drink diary and everything you put in your mouth, and how the bowel reacts and put down whether you had bowel movements that were like this and that, (not to be too detailed on here), and if you had spasms, cramps, wind, flatulence, constipation, etc,
It will need to be true and detailed correctly for them to fully know your symptoms and then refer to a specialist to get a proper diagnosis.. and once you get the diagnosis confirmed then you can start to manage the condition and move forward in your life - it may not be plain sailing there will be good days and bad days, with your bowel but you will soon adjust to dealing with them.
My neice has been diagnosed with IBS the constipation format, when she was 16, she is now 24 and managing fine with her diet, and lifestyle.
let us know how you get on with the food diary and your gp, we are all on here to support you and understand what it is like to have bowel days.!!
gentle hugs xxx