If you say someone suffers, it means that they are enduring physical or emotional pain. If you want to say what is causing the suffering, you add the preposition from and name the cause.
Freddie is really suffering.
(The cause? Nobody knows or they are not saying.)
Freddie is suffering from his injury.
Freddie suffers from an illness.
Freddie suffers from his bad decisions.
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[url=http://www.english-test.net/forum/ftopic9133.html#24000]Suffer from / suffer[/url]