light and temp question and behavior?

This is one of those mish/mosh questions and i have no idea if i am classifying it correctly in the 'Enclosures' forum?
I currently have a 75w zoo med repti basking spot light in a dimable fixture resting ontop of the screen enclosure portion, and directly above Karma's 'spot'. we have only had him 5 days now (2 yr male) and he had been fine on this 'spot'. I stuck the thermometer (the one with humidity and temp) in the top middle portion of tank and it reads something just above 88. I have a digital probe one on the glass 'middle zone (top to bottom ) on the heat side where he basks.... it barely hits 90.
AND then..... last night he was glass surfing and climbing all over the enclosure and rubbing his face on the glass and scratching.... i thought maybe he just wanted out... took him out and was clam for a minute but then kept squiriming for me to put him down.
Okay, so my question is... do i need the 100w basking instead of the 75w.... is it just not hot enough in the tank in the warm side? was something wrong with him or was he just cold?

Before changing bulbs, I'd take the probe and attach it right to the basking surface (stick, floor, rock, whatever that may be). The basking surface temperature is what you'll want to base your readings and light settings off of. If that turns out to be too low, then you'll want to step up the wattage.

I attached the probe half way (hanging) under the basking light ... Between the bulb and the beach surface... Temp reading was 97-98? ... And that is closer to the bulb... So, should I chnage to the 100w?

You can try it, but I'd get a definitive reading of the basking surface first if only to give you an idea of how much more you may need. Hanging the probe will help with air temperature which is helpful, but you'll also need a surface temperature reading. I use surface temps to guide me when I'm adjusting the lighting.

Okay... Right on the basking site it is a constant 98.7.
Sooo, should I get the 100w... Maybe on a dimmable fixture?

That's pretty close. Yeah I'd probably bump the wattage a bit and either raise the fixture a few inches or put it on a dimmer (you don't want to dim it too much if you can, just a tweak as needed).

i was still on the fence on going up so high.... i did see when i went to the store an exo terra bulb that rates 75% warmer (well, claims on box) than the 'normal' 75 basking light (i was using the zoo med reptile 75w).
Sure enough... that was the trick... it does heat just enough warmer .... and not TOO hot. I was getting a reading of about 110 on basking spot and then Karma kept sitting on the probe lol.

Sounds like you've got it locked in now =)