Hi there, first time poster but I'm just looking for some advice/reassurance. I'm a 20 year old male and pretty physically active - I play football and baseball weekly and go swimming at least twice a week. My diet isn't spectacular; I'm a student so my food budget isn't that good, but I tend to have a very mixed diet, with a fair few vegetables and fruits but also a decent number of kebabs/pizzas etc.
I've always had slightly inconsistent bowels and bowel movements, sometimes having large, solid stools but having diarrhea occasionally as well. Never any blood, no mucus or anything, and it's been like that for as long as I can remember. Maybe that's even normal, I'm not sure. I also had occasional bouts of constipation which lasted a few days at most.
About 4 weeks ago, I developed severe constipation, worse than I'd ever had in my life. For 3 straight weeks, I didn't have a single 'decent' bowel movement. I would sit on the toilet for perhaps half an hour at a time, only managing to squeeze through a tiny bit of diarrhea or thin stool. I even tried sitting in different positions, including with my legs up, to try and assist the bowels. My diet hadn't changed particularly in the lead up to this change in bowel movements, though I had started focusing on my university coursework and exam revision.
After these 3 weeks, I went on holiday to Spain with my family. During the 10 days I was there, I developed more regular meal times (as a student living on my own, I often stayed up to late hours such as 4am and beyond) and sleeping times but although the constipation eased up slightly, it still greatly persisted.
I bought a bag of prunes and ate several each day and the constipation largely disappeared, though the stool was often diarrhea and had little form (sausage shape like usual). Nonetheless, it allowed me to empty my bowels and feel better. After not eating the prunes for a couple of days however, I noticed the constipation began to return and I found myself straining again when using the toilet.
I'm now home from Spain and terrified that this constipation/diarrhea cycle is something serious. I have little abdominal pain - only the usual when I've not had a bowel movement for a lengthy period of time, and few other symptoms. I find if I haven't had a bowel movement for a long time my appetite decreases due to the bloating feeling. I've always been anemic to a degree due to a rare, non-dangerous blood condition I have, but have not noticed any increased weakness, dizziness or loss of motor functions. I have also THOROUGHLY checked my stools for signs of blood (both dark and fresh) and have not found anything more than a few spots on the tissue paper after straining for a long time. The stool, when passed, is a fresh brown colour most of the time.
I'm scared however that this could be something very serious, but was wondering if this could be a case of IBS? I'm not a regular smoker or drinker (socially at most) and there is no family history of colon cancer as far as I'm aware of.
Any help, advice or reassurance would be greatly appreciated! Thank you.