A light dimmer is a temporary quick fix on getting the heat mat down for a short amount of time. Light dimmers can also make your UTH go up if used for a prolonged amount of time. I would highly recommend getting a thermostat and a piece of flexwatt from here:
http://www.reptilebasics.com/Thermostats-p-1-c-250.html
Yes they are a bit expensive, but they do the job and hold temps perfect. I've used all the ones Rich sells, and have never had a problem with any of them failing or holding wrong temps. Also ALWAYS ALWAYS ALWAYS place the probe for the UTH directly on to the UTH, NEVER on to substrate. If you do that, the UTH will heat up as high as it will have to in order for the probe to be at your set temp on the thermostat. How much substrate are you using? an inch, 2, 3. 4 inches?
Also try not to handle your new baby snake. It will stress it out and you may have problems getting it to eat. What size tank/tub do you have him/her in? I'd get the temps under control first, give it a day or two then offer your baby snake a mouse hopper or a rat fuzzie. If he/she eats it, GREAT! Leave it alone to digest it's meal and repeat the feeding again in 5 days. You will want to do this till your snake has eaten back to back 8 times with no issues before really taking it out and handling it.
Best of luck and please don't hesitate if you have any questions or problems!