Is it all really just stress?

I thought after a hellish four months of intemittent d* and constipation after taking two tiny antibiotics that I had finally taught my body the dos and don't but I ate an innocent tuna and sweetcorn sandwich yesterday and some chips(fries) and chocolate in the night (these foods usually bulk me up and give me normal bms) but this morning I woke and had painful gas... I had a bm which was just constipated "rocks" but an hour later had a horrible spasm followed by a horrible pain just before I passed gas :(. I don't know what I did wrong but I have been stressed about moving house and starting a new job but didn't feel this ALL week despite the same stresses.. My periods are rarely off track but for the past three months have been both early and late.. Last one I had was only after 20 days :/ ..UGH. is IBS really this cruel? I'm an anxious state every morning before work cos I don't know what's gonna happen next

Well reading what you ate I would say trying eating more fiber, fruit and leafy greens and drink water those foods will mess up your digestion and not only that sress and anxiety and being tired can mess us up as well.