My cat Rosie has flea allergy dermatitis, when she first started having problems as a kitten I had to do the same, she had tests too. And vet scared me as I get really dry skin on my hands, said it looked like I could have caught it too from the couple of patches on my hands! All negative thankfully! Thank god I never saw her again! Thought she was a human Dr as well!
I bathed both my girls when got them at 8 weeks, had fleas when I got them and was best to use shampoo. Was a horrible experience, they were tiny though and my sis helped, don't think I could do it now when they're nearly 13! They'd kill me!