since when does the size of a head decide if a dogs a pitbull they make it up as they go along you wanna check that bitch out to see if they've chipped her, that sounds dodgy
if she's not bothered or scratching it's probably hormonal and the spots are probably all over but first time you've seen them because of the hair loss if she's not down i would'nt worry
http://cgi.ebay.co.uk/WESTERN-DIGITAL-1TB-1000GB-External-Hard-Drive-USB-2-0_W0QQitemZ150433278235QQcmdZViewItemQQptZUK_Computing_HardDrives_RL?hash=item230685a91b#ht_2816wt_1165
just sourced this for you dont think you'll get much cheaper 1tb for £65 delivered.