What causes these recurrent syndromes? i get sudden panic, somnolence, weakness and diarrhoea. they last an hour or so.

It is unclear from: What you are sharing. Although it could be psychological and related to an earlier illness and anxiety about it recurring, i would recommend a full physical evaluation to rule out a medical explanation before assuming it is just psychological in origin. If there is not a medical reason work with a psychologist to treat anxiety.