"to suffer something" / "to suffer FROM something"

Hi:

"To suffer" means 1. "to undergo or experience, mentally or physically, something unpleasant, bad, or painful. It also means 2. "to undergo or experience or be affected by an illness or disease, especially a prolonged one". Am I right about what I have said?

I'd like to know that what's the difference between these two definitions / meanings of the word "suffer". Is there really any difference or is it just that I don't seem to understand them clearly?

When we talk about the structures that this verb might be used in, we say that 1. One may suffer something or 2. One may suffer FROM something.

My question is that is the form "to suffer FROM" only limited to the second meaning (to undergo/experience an illness or disease) given above?

I'm giving here some examples to show more clearly what I want to ask.

1a. Some patients suffered severe side-effects from the treatment.

1b. Some patients suffered FROM severe side-effects from the treatment.

2a. Their team suffered another humiliating defeat last night.

2b. Their team suffered FROM another humiliating defeat last night.

3a. About one fifth of adults have suffered occasional periods of unemployment.

3b. About one fifth of adults have suffered FROM... .

4a. He suffered a heart attack yesterday.

4b. He suffered FROM a heart attack yesterday.

5a. Twenty five policemen suffered minor injuries during the riots.

5b. Twenty five policemen suffered FROM minor injuries during the riots.

6a. No one should have to suffer such degrading treatment.

6b. No one should have to suffer FROM such degrading treatment.

I hope I've able to make my questions clear enough. Still, if there's anything in my post that is not so clear, please point that out.