Hello!
I feel alleviated today
"alleviated" - past tense
"I feel" - present tense
Remember, you shouldn't mix tenses and "alleviate" is a verb. It's not an adjective so you can't "feel" it.
Instead, you can say...
I felt relieved today.
My headache was alleviated.
I feel relieved today.
My headache is alleviated.
Hope that helps 😊