When i get a mosquito bite, it itches like crazy, and immediately turns into a large, red since i was small. could this indicate an allergy, what to do?

Mosquito bites: A large local reaction to insect bites including mosquito bite does not need allergy treatment. You could apply cold compress, topical otc hydrocortisone. If the swelling is large and painful, you might need to see a local physician to be evaluated. If you develop systemic symptoms like hives, belly pain, difficulty breathing with mosquito bites, it is dangerous and you should see an allergist.