get sick : 軽い病気になる

Take this medicine in case you get sick.

in case...   もし...なら

become ill : 重い病気にかかる

My aunt became ill and has been hospitalized.

be hospitalized 　入院する

get over : 病気が治る

I got over the flu.

I am getting over it. 　治ってきてるよ

the flu  インフルエンザ

cure : 病気を治す　(heal : 傷を治す)

He took some medicine to cure his stomachache.

The doctor cured him of rheumatism.

cure

cure 人  of ...   人の...を治す

stomachache 胃痛

rheumatism リウマチ

sick again : 軽い病気をぶり返す

I feel sick again.

catch a cold again

My cold has returned.

relapse 再発、癌などが再発する  He had a relapse of cancer.