Not really sure if this the right section to post this in but need advice from other parents

My son is older late twenties and is in military currently. He recently got married and his wife weve known for awhile now. We was very happy with him deciding to marry her and felt she would be great wife for our son. They did get married because she said when he was visiting her in the state she lived she ended up getting pregnant.

Since the marriage she has cut all communication with us and what little communication there is shes been very cold toward all family members.

I am questioning the whole pregnancy issue because she says she got pregnant and then 5 days later took a urine test , right when my son said they should wait to get married , and she told him the urine test was positive. They married the next day based on the fact that she told him she was pregnant. Since this time and with her attitude towards everyone im second guessing the whole pregnancy issue.... last i knew you couldnt find out you was pregnant within 4-5 days of conception with a urine test bought at walmart ? And then she sent me pictures of an ultrasound at 6weeks and it just dont seem to match up to being a 6week old fetus... conviently the info that is normally printed on the edge of ultrasound picture has been cut out of the picture...hmmmm strange.

As you can imagine im just stuck in a really bad spot
Do i say something to our son ? If i do she would for sure deny anything

Do I just be quiet about it and wait till the baby born and see when the birth is if the dates match up that they would have been together?

Shes already trying to find ways to cut contact with our son by things she says.... i cant stand the thought of him cutting us out of his life. Hes in such a difficult dangerous time of his life with being deployed soon. I dont know how to deal with this .... just need advice