Re: Pregnant or stressed?
I've experienced a "light" period a few times in life when life got crazy stressful on me. Every time the following month was normal.
Regarding your abdominal pain, chances are you aren't eating well right now due to stress, and that can cause constipation and other intestinal abnormalities. Dehydration can also cause headaches. You could try drinking a ton of water, and eating a bunch of fruits and veggies several days in a row. You could also try a fiber supplement like Metamucil, but again drink a ton of water. If your abdominal discomfort/headaches continue after trying this, then see a doctor.
Regarding whether or not you're pregnant, take an at home test or go to a community health clinic that offers free pregnancy tests to ease your mind.
If your pain gets so bad you can't sleep or go to work, then of course go to urgent care or the ER as that can be a sign of apendicitis or an ectopic pregnancy.