Belly/leg rash and calus on elbows - HELP

I adopted a great dane puppy for my daughter from a friend. They had just moved to a new house (found out there had been A LOT of cats there previously). Poor thing at 8 weeks old was 1 or 3 that survived to 8 weeks. Now at 4 months he is the only survivor of his litter of 15.
I wormed him numerous times with both pyrantal pomate and safeguard. Have seen no visible signs of worms. Pretty sure he is on the mend from that. Gums looking much better and eating me out of house and home now. LOL
Right after I got him he had a few ant like looking bumps on his belly right around his penis. Continued bathing and trying to keep him clean and dry. They seemed to scab up and go away. Now they are back and worse than ever. Not sure what to do? Is it possible it is a worm I am not getting? I have ready it may be flea allergies.. But not sure.
He is also developing calusus on he "elbows". I have ready that with Great Danes they need a bed to cushin to prevent this. He does have a bed 2 in different areas of the house to try and prevent him from just plopping down on my tiles floor. But he still has these nasty spots anyways.

Below are likes to pics of his belly and elbows, any advice would be appreciated. Put anti-itch cream on his belly tonight.

http://photos-g.ak.fbcdn.net/hphotos...09996874_n.jpg

http://photos-e.ak.fbcdn.net/hphotos...52788471_n.jpg

I've just had a look at the pics. This looks like it could be a skin infection or dermodex mites, but it could be something else, I'm not sure.

The best advice I can give you is to take the dog to the vets and see what they think. The dogs skin does like sore.