Is the UTH regulated? How are you measuring the hot side temps?
I would recommend a temp gun to measure direct hot and cold spots: I got mine from Lowes for $30
I would be worried about the regurge and the diarrhea: those are not normal and a healthy BP shouldn't show those symptoms. Though, sometimes poop when just passed does look runny and an odd color (sometimes yellowish), and looks different after it firms up and dries out.
Also, there's no reason to assist feed unless the BP has lost a significant (deadly) amount of weight: how much weight did he loose in the time he wasn't eating? They can go months without eating and be fine, though I like my babies eating like pigs to pack on weight. How old/big is your BP (in grams)?