It's been a long time since you posted your concern but coming across it now, I thought I should post back to hopefully help you out a little bit. If your poops go from really runny to constipated it is a sign of being exposed to a toxic inhalant or ingestant. It sounds to me that you might have come in contact with something very toxic. I have experienced the same issue as you. Going from non smelling poop to sudden severe gastrointestinal cramps with poop that is very fatty, oily and light brown in colour with an extreme Camphor smell at times and others very lingering sulphur smelling ones. Make sure you are always in a well ventilated area when you smell that smell that makes your poop smell as such afterwards. ALso take note if you are suddenly losing weight fast.
Do you live with room mates / family or by yourself? If you live alone, the cause could be external from your home but if not then maybe you should be more careful around your home.
Another reason for extreme diarrhea to extreme constipation with disgustingly foul smelling poop can also be Arsenic os some kind of heavy metal poisoning unfortunately.
Hopefully your problem has passed and you are in better health.
A concerned person.