the dreaded sulphur burps, diarhhea and vomiting!!!

I have been getting this once yearly since I was about 15 when I contracted giardia. I am wondering if anyone here has experience with it and or what you might think are the causes, and effective treatment, cure.
I cannot stand this sickness, and I was getting it quite regularly over the past 4 months. Diarhhea like water that would last for 6 hours on and off and then floor me for about three days.
Our water supply is rainwater which we filter slightly. Its fine. I am the only one who gets this. For the last couple of nights I have had the sulphur burps and been having a lot of wind. I am trying to hard to take care of my health and to avoid this. But it just is still hanging around!
I made a nut version of sticky date pudding, a small bowl full, ate it all ( I overdid it I know!) and then had burps really bad and felt ill.
any thoughts?
thankyou
Beau