Sick keep coming back

Hi mummies, i have a twin boys they are 2 years old. Since 29 Jan 2021, 1 twin is down with fever. After a few days, start coughing and runny nose. His cough has alot of phlegm. Went to see GP and it start recovering but still have slight cough with phlegm. Then 2nd twin start to have fever, cough and runny nose. They have been recovering but the sickness keep coming back till now. I understand they are in CHildcare so it’s easy to get sick. But they have been sick for a month plus nw. Have try GP, Pd or even TCM. I dunno what should i do next? Now they are having fever. Went to GP and got ibrufen and paracetamol. #pleasehelp