stop an American bulldog itching problem?

i have an American bulldog who has a serious itching problem. i have taken him off foods that have corn and wheat in it, and bought him special avocado shampoo, which seemed to help a little but still itches, can someone give me advice please

Unscented baby lotion, Benedryl, Hydro-cortisone. Epsom salt.Get all of these things. Benedryl needs to be the tablet, not the gel tabs. Weigh the dog. For every 15-20 pounds, give your pup one tab of benedryl. So for a 30-40lbs, 2 tabs... Do not bath more than 1 time a week. It dries out the skin too much and can make it worse. Is there one spot that is itchy or is it the whole body? For the whole body... If you can, when you bathe your pup, try to get him to soak in the epsom salt. There will be directions on the salt for how much to use. If it's a spot... Soak a rag in warm water with alot of the epsom salt, place it on the area and hold for at least five minutes. After bath, each day, and anytime you think your pup would like it, RINSE... Only rinse... Just get the majority of dirt off. Rub in the lotion as best as you can. Let it stay on the fur for at least 5 minutes, go for a walk around the block while you are waiting, then towel off the excess. If you are noticing spots that are worse, use the hydro-cortisone cream on those spots.While you are doing all this, check for fleas or ticks. Check out his outdoor area for ants. If it's fleas, treat the dog, your house and the outdoor area. Garlic is controversial but it does help if it is parasite or insect related. a low dose of garlic once or twice a weeks can help. (one tablet)If this keeps up, getting one of those funky collars can help, especially if your pup is chewing on himself. If it persists for a week, regardless of treatment, go to the vet.