Is 昨天我有过敏反应了， 所以，现在我不吃西瓜了 grammatical?

Question

昨天我有过敏反应了， 所以，现在我不吃西瓜了。

I asked whether this sounded unnatural or not and was voted as 'a little unnatural'.

And was answered with this;

昨天我吃完西瓜有过敏反应、所以我现在不吃西瓜了。

Is the first form acceptable grammatically (even though it sounds better the other way) or is the grammar wrong as well?

Also do you not put 了 in the first portion because 吃完 already states the action's finished or is there some other reason I'm unaware of?

Answer 1

昨天我有过敏反应了， 所以，现在我不吃西瓜了。

Your sentence is grammatical. However, you haven't explicitly said to what you have your allergy. It's not something with grammar though. To be clear and concise, you could say: 我昨天吃西瓜过敏了，现在不能再吃了。

The reason why 了 is not needed at the end of 昨天我吃完西瓜有过敏反应 is that 有 already denotes the existence of 过敏反应, so 了 is unnecessary. But if you add 了， 昨天我吃完西瓜有过敏反应了 sounds emotional, implying that the allergy surprised you, it's really a big deal, the ellergy is what you were expecting, and etc.

Answer 2

我昨天吃完西瓜后有过敏反应，所以现在不吃西瓜。

Yet for me, in daily life I would just say:

昨天吃完西瓜过敏，今天不吃了。

Answer 3

You were minded to say -- you had an allergic reaction after eating watermelon and so decided to stop eating it.

But your original sentence ended up saying -- you had an allergic reaction of some kind and so stopped eating watermelon; thus giving the impression that the allergic reaction was not necessarily due to eating watermelon, which we gather is not the case because of 现在 which retrospectively connects the decision not to eat watermelons to the allergic reaction.

So it's not about grammar here but wrong or inappropriate placement of words which alters the idea meant to be conveyed.