The first time I had an obstruction I had pains around my belly button area that would come in waves much like labor pains. I couldnt pass gas or stool at all. My gut was huge and the sounds coming from my gut were loud. The pain had started much like bad gas pains that just got worse as the day moved on. By the time I got to the ER I was hurting really bad, I didn't vomit until I had a been at that ER for a couple hours.
I would just pay close attention to how you are feeling. If the pain gets any worse, please do go to the ER. Explain ALL your symptoms and they will probably do xrays or a CT Scan to see if there is an obstruction. Everything you are describing sure sounds like the beginning of an obstruction. But if you don't feel the pain is that bad, then hold off until things change. But dont let it get out of hand.