I waiting to see a gi dr for positive fecal occult blood test. having heavy aching and bloating feeling in lower ab if it gets worse should i go er?

Probably not: unless you have severe colicky pain and obvious bleeding, you can wait till you see the GI.

It depends: If you start to see blood or something that looks like coffee grounds in stool, get weak or dizzy or get severe pain or fever, or cannot pass any stool you should. Otherwise, let the doc who referred you to the GI that you are now having more symptoms and see if your appointment can be moved up.