けれども、急にめまいがして、再び古びた椅子に座りこんだ。

But he suddenly felt dizzy and he sat down again in his old chair.

なんだかめまいと吐き気がします。

I feel sort of dizzy and I feel like throwing up.

急に立ち上がったら、クラッとめまいがした。

I suddenly stood up and felt faint and light-headed.