About 3 weeks ago we noticed our male cat licking, scratching himself a lot, so put flea medication on him and sprayed the area at the base of his body near his tail (where he had created sores from biting the area) with hydrocortizone spray. Since then he will have nothing to do with us, he sleeps under the spare bed all day, and when he comes out and we try to pet him he runs away and won't let us touch him. Before this, he was friendly, affectionate and sociable. He is eating, drinking and using the litter box as usual. What can we do to get him to like us again?
Right now he associates you with the bad spraying experience.
Give him his favorite cat food or treats and sit by closely. Don't try to pet him. After a few feedings, slowly try to pet him. Pet him gently and sweetly. Also try playing and interacting with him. You need to make him associate you with good things.
Just because he is licking and scratching doesn't mean he has fleas. The sprays are often toxic to cats and may burn or be painful. You can spot fleas by examining your pet's hair closely - they are little tiny brown jumping insects. Cat fleas are a particular species of flea and don't infest humans so you have nothing to worry about.
I would avoid off-the-shelf sprays as they are typically just insect poisons which are bad for your cat. Avoid administering treatments unless you know for sure what what the ailment is.
If he is licking or scratching a lot or loosing hair take him to a vet.
Did you put the correct dosage on the cat? It could be something as simple as the smell of the medication. You have to remember cats have an excellent sense of smell. He may just be avoiding you because he thinks your going to put more on him. Try washing your hands prior with water to get rid of the sent of soap when playing with him in case he is confusing that with his flea medication