I have been bit by a mosquito probaly and i have 4 bite around that area which is my wrist and the bites is leaking yellow fluid/crust and my wrist has swelled up anything?

If you had been bit by the mosquitoes then you probably scratched the sites and now there is bacterial superinfection. You should clean those lesions with hydrogen peroxide and apply antibiotic ointment then cover with dry bandage daily. For swelling and itching, you can apply local ice pack as needed. You may need oral antibiotic if you have fever or the redness & swelling extend up the arm.