Digestive Disorders :: Nausea Quite Often

For the past couple of weeks I've been having some mild nausea most days than not. It doesn't last very long but does come and go throughout the day and it doesn't affect what I can and cannot eat. It doesn't seem related to food, smells, etc. just totally random. The very first time I felt nauseous was after smelling some nutmeg and that time I felt like I was going to throw up. Since then, every episode has been very minor.

I eat fairly healthy. Organic foods, very little dairy, cutting down on wheat, lots of veggies (broccoli, cauliflower, spring mix, carrots, etc.), not too much meat (often just chicken). One thing I eat quite a bit of is Japanese sweet potatoes, sliced and baked (sometimes with the inside of the skin getting black). I also exercise quite often (biking, running, weight training, etc.)

My main concern is that I could possibly have stomach cancer. Is this possible? I've read the other symptoms but it seems like they're only obvious once the cancer is in the later stages.

Or could it be something else? And if so, what would cause such minor nausea with no other apparent symptoms?