AnoxiaSan, Miralax is not intended to be used as is a conventional laxative, rather it is frequently prescribed in preparation for a diagnostic procedure, such as a colonoscopy. Occasionally it is prescribed in a very specific situation such as that which you are presently experiencing, but do not use it for more than 2 weeks. Do a web search and see what you find about Miralax - not reassuring.
A good cleansing enema is a far more natural and effective way of relieving constipation, but not the chemical disposable units they sell in the drug store. The old fashioned enema bag is a time tested proven way of providing immediate relief for the occasional case of constipation.
Regarding colonics, in most states doctor approval is not necessary to receive a colon hydrotherapy treatment, and I would encourage you to seek out a therapist and give it a try. You may be surprised at how much old waste matter comes out.
In the meantime, here are a couple of links that may be helpful if you haven't given yourself enemas previously: