I don't remember doing anything in particular to make me feel so tired, but ...
この場合、次のような言い方ができますよ。
ーI didn't do anything special, but I got really tired all of a sudden.
「特に何もやってないのに、どっと疲れた」
I didn't do anything special, but ... で「何をしたわけでもないが」と言えます。
ーI don't remember doing anything in particular to make me feel so tired, but I'm really feeling it suddenly.
「特に疲れるようなことをした覚えがないが、どっと疲れた」
I don't remember doing anything in particular to make me feel so tired, but ... で「特に疲れるようなことをした覚えがないが」と言えます。
ご参考まで!