You poor chook - constipation is so nasty!

really avoid pushing on the toilet if you can - when you push you actually close a valve in your heart - hence the dizziness.

There are lots of "natural" things you can do. If you have grapes, prunes, prune juice, licorice (sp?) at home have some of those. They can all have a laxative effect (but this does depend on the individual).
Another thing (and something I ALWAYS reccomend) is warm water drinks. Boil the kettle, pour a mug of water and start drinking it once it has cooled a bit (or pour 3/4 boiling water and 1/4 cold water). This usually works quicker if you do some gentle exercise afterwards. Even walking around the back yard might be enough to get your bowels moving. If you drink several cups it might kick start the bowels as well.
I've got a friend who also puts a hot pack on her belly which does little more than relax tummy muscles and allowing you to "relax" to go. I've never had success with this.

HTH and hope you get some relief soon.

MG

ETA Just a thought renee - do you have any "trigger" foods? I know whenever I have a particular brand of lasange I end up on the toilet within 30 minutes. If you have a trigger food and there is some at home, give it a go.