Whether these sentences are correct

[Mehboobleo]

I am ill today.

I am sick today.

I have been ill for two days.

[PHIL73]

Hello Mehboobleo,

I think they are all  correct. 

Maybe "I'm (or I'm feeling) sick" would mean that you're feeling temporary indisposed and even nauseous, whereas "I'm ill" would mean that you have a more serious and long-term disease.

But they are often used interchangeably. Anyway the meaning is that you're feeling unwell.

I hope those are only sentences and you're feeling OK, unless I wish you a quick recovery 

 

[merriemo]

they are all correct.

 

[Vignoban]

They all are correct 

[1karola]

I also thing they are all correct.