Hi Monican
As you have been exercising is it possible some of the weight gain is muscle?
I notice you said you are 'generally making good food choices' so I agree with Jules that perhaps keeping a food diary will help you see what you might be eating that is helping to add kilos.
My only advice is to do something now while there is only 4 kilos in it, before it becomes more and more, I am sure you know what I mean, I am guessing we have all been there.
Good luck, I am sure that others will have some good ideas for you as well.