Hello there, I am dr.milan an infectious disease specialist answering your question, I need some clarificatin from your side, 1.Is widal test is done by tube test? Because slide widal test is not confirmatory for typhoid. Is widal test done after few days of first test? because rising(titer) result like 160 after few days 320 like. In this case according to your history it is mostly because of salmonella infection which is resistant to given antibiotics. So now you should go for culture examination of stool sample. Because from other sample salmonella mostly will not come. If culture comes salmonella positive than you should go with drug sensitivity under physician guidance. For salmonells it is necessary to give long term antibiotic to clear from once body at all. In this case salmonella( if present) is remaining inside some body organ from where it releases intermittently. so fever comes along when it release into the blood. So in short go for culture test of stool and follow complete schedule of your physician. Hope i have given appropriate guidance to you. if you have any query you can consult me anytime. Give me star rating according to your satisfactory level. Thanking you.