Make sure you have enough water with the chia seeds, and not too many of them in a day.
i had a teaspoon in my scrambled egg in the morning, the same for lunch and a spoonful in my omelette for dinner. I had enough water throughout the day at work, but only one glass of water immediatley after my dinner and another in the evening which was nowhere near enough:
When i went to bed i was cold so put an extra duvet on the bed. Woke up cold with them on the floor so put them back on and then woke up again sweating, bed was wet, clothes were wet, and i had an awful, awful pain in my stomach. I went to the toilet where i had diarreah (sp?) and more pains, i felt like i just wanted to throw myself on the floor, as well as be sick. I was cold but sweaty, my vision went funny (seeing white) and my legs went tingly then numb so much so i had to try to walk around for a bit. I thought i wanted an ambulance. I thought about testing my blood but was too ill to bother - and stuck on the toilet. I woke my sister up to get me some water and as soon as i started drinking it i started to feel better and eventually could go back to bed.
Slightly dodgy feeling belly today but i've had some immodium, no seeds today, and feel pretty much ok.
I am convinced that this is due to lack of water with the seeds, eating eggs for 3 meals for one day wouldnt do that to you, so be careful with them and dont forget to drink your water!
Edit: green tea with them could also be the problem. I had two yesterday, and did notice before that i'm ok with one, but if i try to have three as recommended then i get looser stools than i'd like. two is also ever so slightly too many as well.