It could be several things. Here are some things to try:
1. Soothe the intestinal lining by taking 1 teaspoon of slippery elm powder (make a tea) twice a day
2. Lack of stomach acid is a likely cause - take some betaine hcl with each meal - or some ACV or lemon juice in water ... or some digestive bitters ... or a combination of all of those. Also, drink peppermint and ginger tea to help with digestion.
3. Do some liver work - milk thistle, lecithin, castor oil packs etc.
4. Chill out a little - sit quietly for a couple of minutes before you eat and do some deep breathing (in and out of the nose) ... release all tension before eating anything.
5. Chew every mouthful very carefully and eat in a quiet setting. Consider taking some digestive enzymes as well with each meal.
Do as much of those as you can and then restart the probiotics after 1 week.
Best wishes
Maya