I rang our D.O. Peter Rees who is a qualified chemist.  I explained my problem to Peter.  At last night's meeting Peter gave me some tablets.  They appear to have cured my problem.  I'm very relieved.  Today has been much better.  I've managed to complete a full day's work including cleaning a window and re - dressing wityh what little halloween stock that we are carrying.  Tomorrow if the problem has finally cleared up, I intend to go fishing.