Hello! I have questions about the next sentence.  Please teach me.

1)     The people saw that the whales were helping their sick friend, but
everyone worried whether the healthy whales would not also be injured or
become sick.

   I hear this is the sentence written by a native speaker of English.  My
first question is whether  negative ' not ' is needed in the underlined part
and  the second question is whether 2) is  correct or not.

2) ... everyone worried whether the healthy whale would also be  injured
    or become sick.

I tried rewriting the original sentence in two ways.  How about (3) and (4)?

3) ...everyone worried that the healthy whales would also be injured or
        become sick.

4)... everyone was afraid that healthy whales would also be injured or
       become sick.