Finally I broke through my 'mental distractions' and made a real good progress on my next academic year preparation. I had to throw away some self-imposed restrictions and now I think I have great workable plan. This is important!
The cherry season ended - and few cherries I tried (with caution) did not cause any problems. Now I tried grapes. After no more than a small handful I started to feel 'not right'. 15 - 20 minutes later the 'dumping' happened. What an unpleasant experience. I am still puzzled why cherries were OK but grapes are no-no.
Every new food is a potential trap and unpredictable surprise.