Ongoing ? Immune issues, what to do?

Female, 61 years, 76kg , 157cm. living in Melbourne Aus. Have had fever, shaking, brain fog, going on for 2 months. Shaking and sweats at night, cramps in hands. Getting slowly better but up and down. Extreme tiredness and also flu type symptoms. Stomach cramps gone now, now mostly vomiting and allergic reactions to foods ie that lip, throat and tongue swell. What can I try to manage or test for causes?