Oh dear. That is not good, but he is probably just reacting to the changes in his life. He was not being tested before, right? He has a new home, new routines, its all scary for him.
Things were rough with Jeddie in the beginning. Bad bite on my hand. I could not test him for a few days and then only by wrapping him in a blanket and wearing leather gloves. I really can't remember how long that lasted.
How long has it been since you got him? It might be better for him in a smaller space, even if he thinks differently. I would suggest the Feliway diffuser, although I have not used it - that's just from what I have read here. I might consider using prozac for a while. I have not seen anyone post about using it for this issue, but I have used it for other things and it works well on an anxious cat. I would try other things first, like Feliway, but I would keep it in mind.
Are you giving him treats after testing? I think that was what turned Jeddie around eventually.