Like Andee said, PowerSun provides both UVB and heat. I didn't know this is what you had since you said ReptiSun. My guess would be that he either could not get close enough to absorb the UVB he needed, or it was too hot up close. Also, do you have anything other than screen between the bulb and him? Glass and plastic block most UVB.
I would really recommend you get a 24" fluorescent strip light and install a ReptiSun 5.0 UVB bulb, and ensure that he can get at least within 7 inches of it without it being too hot. You can get these at most pet stores for relatively cheap, and I would get one locally as soon as possible just to correct the situation.
If you get a dedicated UVB bulb, I would recommend returning the PowerSun and just using a standard house bulb for heat. It should be far enough away from the UVB that he does not get hot when under the UVB. By the way, from the last of the newer pictures he does look like a male.