Aggressive cat

Hello everyone! My cat is five years old and she lives with us since she was 2 months old. She was always a very calm cat. She never really liked petting and we respected that. My son is two years old and he really worships her. Her name is the first to say when he wakes up in the morning and he wants to play with her all the time. Most of the times she tries to avoid him and run away or hide because he tries to catch her in clumsy ways. Sometimes she bites him and we try to explain him that she needs her space but it is very difficult for him to understand. The last two weeks, after a birthday party with a bunch of children, she's become really aggressive. She attacks all the time with hissings and scratchings!The first she attacked my son who was playing with a balloon and tore his pants off and wounded him a lot.  His legs were bleeding! She wouldn't stop  and she did the same to my husband when he tried to take my son away and stop her. After that she attacks us every day. I am afraid in my own house by my own cat...We went to the vet and told us she is healthy and cats do sudden attacks and become aggressive some times. What do you think? I really need help...I don't want to give her away because I love her but i am afraid especially for my son.

I'm so sorry that you have found yourself in this situation.  Please be aware that nearly ALL cat scratches have some very unpleasant bacteria in them and frequently need antibiotics quite quickly, especially if they are deep or if the receipient has a low immunity eg a child.  We do not give human medical advice, but its worth running this past a doctor.  If you live in the UK, you might want to call 111, to be triaged..........................Meanwhile, am not sure whether your cat feels threatened by your son, or whether she is trying to play with him - or even testing out hunting skills!   Here is what a worried  cat needs to feel secure:  1)  a place where they can get away from any perceived threats (your son, possibly);  2)  a safe pathway to the food, litter tray and outside (if this is an outdoor cat) from their safe space without having to cross any area it considers to be the threat's territory.   It may well be worth looking at the icatcare website or talking to your vet for information about how to keep them safe from one another in the same household, and about how to read a cats body language because the signs can be quite subtle.   Meanwhile, in the interests of safety, I would be constantly keeping the two separate when not directly supervised, and I even wonder if it is worth your cat going to live elsewhere for a time?