Growing bug bite & 28 weeks pregnant

Hi everyone! 2 days ago I spent some time in my pool and everything was fine until yesterday. I woke up yesterday with this bite/rash on top of my leg at 1/3rd the size is is now. By bedtime is was about half this size. It is now 1 1/2 inches long and itchy (I have been avoiding itching as much as possable while awake ). It does stick up about 2 or 3mm but I am unsure of what may have bit me. Any help is appreciated!