25 week Scottish Terrier

Question
Hi. My Scottie has been a happy, active and energetic little guy since the day I brought him home. He's up to date on all his vaccines and has a good diet. However, he's been very itchy the past 4-5 days. (since I let him spend an entire day in the backyard with our outdoor dog) I always give him a bath immediately when he comes in from the backyard b/c we have poison ivy somewhere out there and he manages to get into it and pass it to me EVERY time. Anyway, he was very itchy and was scratching and biting quite a bit. Two days ago when I woke up I noticed he threw up and later that morning he started acting like he was going to vomit and I took him outside quickly and he sort of threw up a tiny, tiny bit. That evening I noticed that he was not eating or drinking. Last night I did get him to take a pretty long drink of water. Today he still hasn't eaten or drank anything since we got up. He's also been pretty lathargic. He just looks kinda like he doesn't feel up to par. My husband and I decided we would give him one more day and if he was still acting weird we'd take him to the vet. We were really hoping maybe he just had an upset tummy and it'd get better b/c a vet visit is going to put a big strain on our financial state. We love our pup though, and will take him if we need to. I pinched the skin on the back of his neck and it went back down. Any suggestions? Could the loss of appetite and lack of drinking be symptoms that pair with some sort of allergy which started with the itching? He doesn't have any redness and I didn't see any fleas or ticks on him at all. I did see three small little scab-like things between his shoulder blades.  

Answer
There are probably 2 things going on here.  The skin may be itching from the poison ivy, which is unusual in dogs, or the pup may have sarcoptic mange.  He should be treated for that even though the vet may not find it on skin examination.

As far as the dog having no appetite, the ve will need to figure out why and what can be done.  I cannot do that on the internet.