It's not really random though.

She's announced she was going to do it before and to be fair she's always had more than her fair share of mental troubles, sadly. As someone who is also cursed with those I know how hard that can be and I didn't even lose a child.

Withholding the cause is what leads to speculation and I don't think it's a bad guess in this case.

Personally I think it's better if they just announced it because believe it or not something like this can also lead to good things. Because it can make people think, realise these things happen and notice the signs in people around them.