What size is your UTH? Is it made for a 10 gallon tank? If you have a glass lid it can help with humidity, but a lot of heat from your light bulb will be lost in the glass because it will absorb the heat. there needs to be a hole where the light can shine directly into the enclosure. If this is possible than you may be able to increase the eat it you may want to consider getting a screen lid and covering 3/4 of it with Saran wrap. Leave the center of the screen lid open so your lamp can sit directly on the metal screen. Your lamp needs to be one with a summer switch as well so you can adjust it exactly where you want it.
Note, that a screen top will not allow you to maintain as much humidity, but may help you with your heat problem.
A month is too long. You may want to consider force feeding him. Keep us posted.