WC balls will go in either direction; they either adapt fairly well or they're a royal pain in the a$$. Taking it to the vet was a good first step. If it had ticks, then (as it's been my limited expereince with WC) it's probably got internal parasites as well. Is your vet a good herp vet? Did he do a fecal to check for worms? It may be a good idea to have that done, so you can get the snake started on meds if needed. Once he's treated for all the ailments that WC have (ticks, mites, worms, injuries, etc), put it in the cage and leave it for a while. Check water, temp, humidity, spot clean if necessary but disturb it as little as possible. Give it a lot of time to settle in and get comfortable, then offer food. Preferably not anything white. You should probably start with a small (weanling size) black or brown rat, if it eats it.... Great!! But be prepared for it not to WC don't normally recognize rats and mice as food, you may have to try gerbils or hampsters. Be prepared to keep said gerbil/hampster for a long time, balls can go forever without eating. Also it's best to keep WC balls on a substrate they are used to (Cypress mulch works best) Make sure they have a good hide or two and all the appropriate temps and humidity levels and eventually (fingers crossed) it should settle in. You should also keep checking it for mites and ticks to be on the safe side, It's really likely that a couple can get missed. Unfortunately snakes aren't like dogs, they don't recognize that you've "saved" them and immediately become your best friend, be prepared for a long journey and hope for the best! Oh and about sexing it - there is no reliable way to sex a ball without popping or probing. If it's an adult snake probing will work best. Hope this helps. Congratulations on your new addition!
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Tosha 
8.10.0 Ball Python (Harry and Fluffy and currently un-named)
0.2.0 Feline (Pippen and Pandora)
0.0.1 Dessert Tortoise (Pope)
7.9.5 Fish (1,2,3,4...)
0.0.1 Frog rescued from pool skimmer
0.0.2 Lizards rescued from pool skimmer