Whitwave I agree with Jane, dehydration is probably behind it. DH had an episode of that about a year before he died, while on chemotherapy. He was taking various drugs and looked and felt increasingly tired and weary - not surprisingly. Then felt so awful he went to bed.
GP was called - they are obliged to see you or visit same day you ask if you are on chemo - did not do a lot. Called in a different GP next day - did not do a lot more. Third day, yet another, who did a more thorough examination and said heart arythmic probably from dehydration.
Straight into ambulance, admitted to ward and put on intravenous fluid for several days. He was quite poorly, but the right treatment meant he stabilised and came home after a week or so. His heart seemed not to cause any more problems after that.
Bear up, Whitewave at least it is being looked into thoroughly now.
PS You may find he needs oedema socks once he comes home - all that fluid they pump in has to go somewhere!