I was only in the military for 3 months and i was medically discharged. a doctor said i might have ptsd. is it possible? my wife thinks i have it

Yes, it's possible: But, the bottom line is that you appear to be having problems that need to be addressed. Whether it's true ptsd, or some other condition, get help. And, get help soon from an expert.

Doubt from boot camp: Did you complete recruit training? Clearly you weren't in service long enough to have undergone a deployment? If you underwent a horrific or life threatening experience it is possible. Ptsd from recruit training - doubtful.

It's possible..: ...if you sustained a traumatic experience during those three months. I have seen veterans who sustained trauma outside of deployment, but it is not common. If you are experiencing problems, then the best place to start is with a comprehensive evaluation at the VA. After you get diagnostic clarification, treatment recommendations can be made. Hope this is helpful. Take good care