I asked what to do about insect bites (mosquito) on knees/lower extremities and the pain goes up to 10 another doctor answered that it was probably not a mosquito and it could be infected. What type of bug do you think it would be?

No way to tell. There are more insect species than animal species and thus there is no way to give you a definite answer. Some bites are more typical than others but the only definite answer is having the body of the actual insect observed to have bitten you. Else it would be mostly circumstantial evidence.