Not too sure if this will give me much peace of mind but really struggling!

Im 20 years old, female, and currently dealing with horrendous tummy problems. Between 2-5 of hours of eating a meal, I have a terribly rumbly tummy then out of nowhere I get this awful pain in my lower abdomen (almost as low as period pains) and it is so painful, bent double shouting in pain, to the point it almost stops me breathing. Lasts for about 2-5 minutes and then straight after urge to go to the toilet and experience really bad diarrhoea which is painful. 
Not the first time this has happened but bouts of this before have only lasted 2 days and then I can go back to normal so just thought I'd eaten something. But current bout hasn't gone away after 4 and is getting increasingly worse. Usually I can eat a bit of toast of drink some arrowroot but now everything I eat starts it off and I'm getting progressively weaker. Been to emergency drs appointment and said IBS. Having blood test for celiac disease and had to take in stool sample in case of infection. Prescribed Buscopan and Imodium but I don't want to just treat the symptoms when I think something serious could be causing this as it comes out of nowhere. I have never had an allergy or had stomach sensitivity with what I eat. I'm so young so surely something not right.

Should I be worried? I think I've passed mucus before but not sure as never properly looked out for it but I know with IBS you can at least eat plain food and I'm can't eat anything. Only reason I don't think food poisoning is I'm never sick. 
has anyone had these symptoms which have lead to diagnoses? 
Any info would be so appreciated