My beardie doesne seem to like food!

Question
I bought my Beardie on the 15th Jan this year and collected him 2 weeks later after spending that time making sure his new home was just right, temp wise and big enough as I had been advised very badly on the first tank I purchased.
At first everything seemed fine he was a happy little chappy and would come up to the front of the tank and generally just seemed quite content.
About a week ago i got up and turned his UV light on as i always do and said morning to him and he didnt move, normally i get a cheeky glance from him as if to say right now ive got an hour to wait before food time! Except this particular morning i picked him up and he was freezing under his belly and quite limp.  I may not have had him year but ive grown quite attached to my little guy.  I took him off to the local petshop as shes a mate and knows loads about bearded dragons and she said he was fine and to give him a couple of days and if he was the same see a vet.  He seemed to get better and so i just kept an extra special eye on him and turned into the parent from hell constantly checking his temps in case it was that and cleaning his cage twice a day instead of once etc.
A few days ago he stopped eating and seemed to stop doing pretty much anything, whenever i went near him he ran away, he had got used to his weekly splash around in his bowl for a bath. I noticed he has gone stripy black all across his belly and under his chin.  I took him to a vet and he said he had worms and coccidiosis. He says no treatment for the parasite is necessary but im still worried about this blackness, some of the time hes ok he seems fine then other times i just dont know what to do, i even cried in front of him the other day and he turned his head to look at me as if to say please work out whats wrong with me!
Do you have any advice?

Answer
Hello Sarah,

What type & brand of UVB are you using, is it a fluorescent tube bulb or a compact/coil light?
How close is the UVB light to him?  What type of basking light are you using for him, a bright white light or a colored light?
What are the temperatures in the tank & what type of thermometer do you use?
What type of foods are you offering him right now?
Does he seem to avoid the UVB light that you can tell?
Is there anything that he can see his reflection of himself in, a mirror perhaps?
Do you have any pictures of him for me?
Is his beard black also?
It sounds like he is stressed out from something, but what, I don't know.  Please let me know what your UVB is, this is important because there are a lot of bad ones out there.  
We will figure this out!

Tracie