Evening! (11.44pm here) Thankyou for clarifying that, blood tests are nothing scary at all. I was thinking it was a more intrusive test, that puts me at ease.
I'll talk to my Mum about getting her tested. I think it would definitely be worth the money for the peace of mind. It's not an emergency situation as it's only that one symptom...
She's peeing a few times a day but she doesn't drink an excessive amount of water, her stools are fine, she's at a healthy weight (if not a little too heavy, I'm still trying to work out how much food she needs) but the only problem is itching her head straight after she eats for about 30 seconds. She does it at other times but it's predominantly after she eats.
In the meantime I'll give the breeder a call tomorrow, I know that the pups went to the vet a couple of times before I got them to check their health etc, I'll find out if she had blood tests done then.
Thanks so much for your input. I just want to do the right thing by my little girl.