Should I be worried???

All my life I have suffered from "no thirst refelex". What this means is I don't get thirsty, even when I am dehydrated. However over the last 2 to 3 weeks I have develope thirst. I am constantly thirsty to the point where I am drinking 6 litres or more a day and I am drinking cordial, something I have never ever liked. I have not mentioned this to my gp but only started to worry when my dad commented on it and mentioned maybe I could have GD.

I was wondering if A) I should mention this to my doctor and B) if this is a possibility from what I have described??

Any advice or input would be welcomed.