Gastroenterology and vomiting. Problem.

My brother working in railway recentely he took covid vaccine covidshield on 23 April then after two weeks he felt gastrology problem and started also vomiting and slight fever..then he took covid antigen blood test that came negative then he took typhoid test then it came typhiod o positive result..also his d-dimer report came positive his d-dimer range was 1270 dat was bit high..then consulted local doctor for treatment of typhoid ..doctor gave him cefixime and ofloxacin tablets for day and night and also gave him injection of ceftriaxobe IP 1g of 1000mg..for five days..his medication has been completed..but after medication.. within interval of 2-3 days..he is feeling gastro problem .and sometimes he also do vomiting ..after vomiting he feels better...is it matter of concern...or is it symptoms of typhiod also..or side effect of hard doze medicine??. Or it is side effect of covid vaccine..??.wt to do..how to cure his gastroenterology problem ...