Suggest Remedy For Rashes

I have a bite or rash on my hip that doesn't seem to be getting better. I thought it was a mosquito bite that i scratched at first, but it has gotten bigger. It is kind of painful from my clothing rubbing on it. It is red raised, bumpy with several small spots in the middle. Should I see a doctor or give it another day or two to see if it gets better? What can I use to relieve the burning discomfort? I am 35, about 150 pounds and pregnant. It has been 3 days since I discovered the rash.