My puppy has allergies and is getting worse

Question
I have a 1 year old boxer/pit mix, he was severely abused when he was younger and by the time the shelter got him at 4 months of age he only weighed 10 pounds.  He is such a wonderful dog, and I have been told because of the abuse he will never be more than 35 pounds.  About 3 months ago, he started itching constantly to the point he was drawing blood especially on his stomach, legs, and ears. He would also break out in a rash on his belly, and he licks his paws all day and night so we started giving him Benedryl to help with the itching as was recommended by our vet.  It helped a little bit, with the scratching.  About a month ago, he started to vomit every once in a while and there would always be a chunk of something it it, so we assumed it had just been caught in his throat and he finally got it up.  Over the last week though he has vomited at least once a day, and yesterday started with diarrhea.  He had not eaten his food, so I made a bowl of plain white rice which he ate, and he has been drinking like normal, and up until yesterday had been going to the bathroom normal.  I called my vet and she said it could be because he has severe allergies it is causing the vomiting.  I think he may be allergic to grass because it wasn't until the grass started getting cut that the itching and everything else started.  If that is the case how can I help my dog?  He has to go outside to go to the bathroom, and he loves going out to play but I don't want him to constantly be sick and the Benedryl is only a quick fix. Does it sound like allergies to you and if so is there anything else that can be done?

Answer
Hello April and  thanks for your questions. This does sound rather sever...has the vet offered allergy testing and steriods yet? My two terreir have allergies..a jack russell and a boston terrier, they both eat blue buffalo fish and potatoe diet and I reccomend this to anyone who has a dog with allergies if it cant be found pro plan makes a salmon and potatoe formula. They also take BenaDryl pills about one a day to one every two days without them for some reason they get nasty yeast infections in tehre ears! and they scratch all the hair off there ears causing bleeding and scabing....my boston terrier had pimples on her thinly haired area on her back legs and right near her butt last year...but after startingb her on allergy pills she calmed down and was treated for a yeast infection in the ear and later...like two weeks later a bacterial infection in the same ear!.... We've been through some hell..... i know how they feel I have allergies too without taking my reaction pills I get hives on my wrists and cant stop scratching all over just as if i was attacked with posion ivy...I have no idea what i'm allergic to but tis not the dog hair or daner...I no grass and long coated cats is really bad for me to be around....unfortunetly my mother had a long coated cat and I work doing lawn care lol. I cant say what my dogs are allervgic tooo I'd say spring and summer outdoor allergies but they get really bad in the winter sometimes aas well.... I went so far to buy a air purifier for our(me and my dogs) room to take dust/muold/daner out the teh air to try help our allergies. I havent heard of allergies as sever as your dogs yet and people email quite offen with alelrgy ridden dogs. I reccomend to just keeping giving the benadryl talk to the vet about getting the testing done...the dog cant have any benadryl pills for two weeks prior to testing thou which can be hard to do if the dog is tearing itsself to shreds.. I would also try a fish and potatoe kibble and bathing once or twice a week with cool not cold nor warm water using a oatmeal and aleo Dog shampoo or just baking oatmeal into teh water...pouring the water over the entire dog is sootihng and be sure to rinse well with whatever yuo use...I persoanly use cool water and oatmeal fr my dogs when there alelrgies are very bad thou som might find it odd...you can put it in a piece of pany hose or cheese cloth also to avoid plugging the drain. Since you have a grassed yard it is of course impossible to keep teh dog off it...our yard hasnt got grass but packed dirt...was that way since we got here  but we do get a few danilions growing around qwhich my dogs like to eat which could be making them worse I'm not too sure. Also if the dog has areas that are scrapped from scratching or genral Hot spots that feel burning taking a piece of paper towel or a small face cloth wetting it and ringing it out with Cold water and holding it onto the affected areas offers some relive as well. If the allergies are really really this bad opt for the testing and steriods...I was going to have my boston tested but she got better before I needed to do this...the testing costs around 300-400 bucks and the steriods are injected a few times yearly i think...maybe thre in pill form I'm not sure but I've not idea how much those would cost.