It sounds like a mosquito bite, but if it continues, I would see your GP to rule out anything more serious.
Can you describe the rash? Is it red bumps filled with pus (sort of like a pimple) or is it small red spots that appear to be under the skin?
A mosquito bite is mosquito bite and doesn’t spread, though mosquitos carry diseases that might cause a rash. I’d suggest you see a doctor to find out what’s wrong.