According to Buddhist teachings, we suffer because of the moment to moment impermanence of all experience. As I understand it, this is caused by clinging to experiences we feel positive about. But wouldn't the impermanence of experiences we try to avoid, by the same logic, involve a similar subtle kind of bliss?
Have you read MN 44?
“Pleasant feeling is pleasant in remaining, & painful in changing, friend Visākha. Painful feeling is painful in remaining & pleasant in changing. Neither-pleasant-nor-painful feeling is pleasant in occurring together with knowledge, and painful in occurring without knowledge.”
"This positive experiences do have a pleasure." The Blessed One has clearly said it.
Then the Blessed One says "If there is no pleasure, the beings will not cling to them."
But then says "Even though they have a little pleasure their drawbacks are comparatively larger."
So the positive experiences are considered Suffering. No need to say about negative experiences.
Refer: Paṭhamanoceassādasutta, Dutiyanoceassādasutta, Nocedaṃsutta, Dutiyaassādasutta,Tatiyaassādasutta etc.