Mosquito bite or something else?

so, yesterday, at the park, it started itching. and it looked like a normal mosquito bite. Its located near my inner left thigh , and the swelling spread. so now my left thigh looks larger then my right. it's extremely itchy but im not scratching it. and idk how to explain it. its just swollen and itchy. i dont even think its a mosquito bite anymore. plz help, thanks!