I don't know if all that straining your doing has actually caused you to develop hemorrhoids. I do know that straining too much over a period of time can definetly cause hemorrhoids.
I would highly suggest adding more fiber to your diet and drinking plenty of water. This will soften your stools and help you to pass them without straining.
If you really want to avoid this in the future then I would recommend you check out this natural hemorrhoid treatment guide at http://fastnaturalhemorrhoidtreatment.com
It is a seven step system that will keep you hemorrhoid free. It is currently on sale although I don't know when that will end.