Thanks everyone - well I worked out what the ill feeling was. I have a wound infection.. Basically I had an op on my foot a month ago and in the past week the wound began to open, drain pus, etc. I ignored it and didn't put two and two together that the ill feeling could be to do with it. When I went to hospital yesterday they confirmed it was a skin infection. Waiting for a swab test result to know what antibiotics I can be put on. All very unpleasant.