I would suggest going to your doctor only he/she can make that kind of diagnosis. Are you on any medications?
When I got married hubby gained weight too from all my good cooking

but eventually he lost it, me I've struggled my entire life.
Don't panic, thats the worst thing you can do, how about slowing down a bit and logging your food intake into fitday.com its a great place to see what is going on. You can customize foods there and they have a TON of foods you can pick from. AND ITS FREE....You might be eating more than you think. Some times when you take a bite here or there or you think your not eating alot you really are. It sneaks up on you. Low fat, no fat doesn't mean no calories, in some cases it could be more.
Bottom line with any weight loss program is calories, you must burn more than you take in.