First we have to figure out whether the UVB you are giving him is adequate. UVB bulbs have both intensity and wavelength. The wave length needs to be inside the boundaries of 280 to 300 nm. Bob MacCarger has named that slice of UVB "UVD". There are several easy to get imposter UVB emitters that give UVB, but do no good because they don't emit UVD. They fool a lot of people because the light meter shows that there is UVB present. I have a UVB meter, and I can measure the microwatts/cm squared. That''s nice to have, but I need other ways to find the precise wavelengths of emitted UVD. Ask this group about which bulbs work well.
We don't know what "reptile carpet" is. But it might soak up urine and urates. Most of us just use newspaper on our cage floors. It's non-toxic, they don't eat it, and it absorbs messes. Plus it's very easy to replace it with clean newsprint. The one rule is NO COLORS. They make the paper toxic.
Your temperatures are good. Make sure the cage is pitch black at night. Those dark red and dark blue screw-in bulbs give too much light, plus we don't know what the iguana really sees in that kind of light. Use Ceramic Heat Emitters to give no-light heat.
iguanas are low nutrient obligate folivors (plus fruit like figs that grow in their natural habitat). In the wild they seem to relish flowers. There is to be no experimenting with food unknown in modern US iguana diets.
Wen they are on the floor, they will eat almost anything, including pins, dust bunnies, peach pits, women's panties (this is true), coins, and more. They will eat the dirt from potted plants. When my ig free-roamed, he was always jonseing for dirt.
Omit kale from the diet. It has a chemical that will strip the calcium out of the food at that particular feeding. It used to be considered safe if fed in small amounts about twice a week, for the sake of variety. But I suspect the literature now is more likely to say No Kale at All. Spinach does the same thing, to a degree I don't know. I never fed spinach in fifteen years. Don't over-feed alfalfa because it is way too high in protein.
Feed enough at each feeding that there are leftovers. The idea is, iguanas should freely feed until they want to stop eating.
His change in behavior is normal. What he is doing is natural for 95% of untame iguanas. He's not scared stiff anymore. His cage is his territory, and igs simply hate invasions. A slow moving hand is very scary, even though some people recommend it. But you are doing it right - low and from the side. It's merely not appropriate for an ig in his stage of development.
Give him a secure place to hide.
He's doing what I call Nose Bashing. It can result in several $600 vet visits. His instinct is to run at any cost. He's not watching where he's going, he's just running. You have to put a stop to his nose bashing. When you want to pick him up, use a small towel and throw it over him, then very quickly grab him and take him out of his cage, and move to neutral territory such as an adjacent room. That limits the duration of his intense anxiety.
If he continues to get frantic when you passively pass by his cage, Line the walls with stiff foam, like 1/2 inch thick backpacker's sleeping pad. He will outgrow this behavior over a time span we can't predict. Using the towel, pick him up twice or three times per day. As I always say, NEVER let him get away, and NEVER let him see you flinch when he bites or whips you. Now is the time to do this, while he is still weak.
Keep the very sharp toenails blunt at their very tips. Do not confuse his claw with the toenail. The sharp nail is about 1/8 inch long, located at the very end of his claw. Try Googling Adam Britton's Iguana nail article.
Thirty seconds is exactly the time it takes for him to stop his initial fight. With both hands, hold him against your belly when he is struggling, and let him roll in your hands when he wants to do alligator rolls.
Never even touch his tail when he is anxious.