Your basking temp is too low - he needs to option of going as high as 130+.

As far as the tail goes, I'm not even going to hazard a guess - my advice is to take him to the vet and get is checked out immediately.

Once he has been diagnosed by the vet and is on a treatment regimen, you need to assess whether or not you are willing to give this animal a long term home. Do you want an animal that is going to reach at least 6' and weigh over 50 pounds? Do have the space to keep him? If not, find a good home for him.

In the meantime, makes sure he is in a proper sized enclosure with proper substrate. At 2' in length, I would get him into a nice stock tank - at least 5' Lx 3'W x 2' H and I would highly recommend getting him into a couple feet of organic soil mixed in with sand. This would provide a nice diggable, moisture retaining substrate that will greatly aid him in shedding, reduce the stress of undergoing repeatedly baths to loosen stuck sheds and correct the moisture issues his enclosure.

As far as his diet, I would supplement it with some ground raw turkey, some roaches, etc.

In the meantime, no one here can help you with his tail issue - please get him to a vet immediately.