You mentioned that your hot side is unstable... Do you have a UTH with a thermostat? Also a heat lamp on a dimmer?

As for humidity: Your screen top is cheaply fixed... Get some foil and duct tape, measure it out, overlap the tape to ensure its sealed. I tape mine onto the trim of the screen, helps hold it down as you lift the top etc. of course you want one ventilation... A hole 1 inch larger than the lamp <if you have one> and one inch on the opposite side for air draw. That will not only hold in humidity, but it will also help hold your heat in and give a more constant temperature range.

I really hope you get him better, be yet to deal with an RI and hope to never have to.